Piezoelectric device, liquid ejecting head, and liquid ejecting apparatus

Abstract

A piezoelectric device, a liquid ejection head, and a liquid ejection apparatus capable of eliminating residual strain of a piezoelectric layer and suppressing a reduction in displacement of a piezoelectric actuator are provided. The piezoelectric device has: a substrate (10) in which a plurality of recesses (12) are formed in alignment in a first direction; a vibration plate (50); and a piezoelectric actuator (300) having a first electrode (61), a second electrode (62), and a third electrode (63), a fourth electrode (80), and a piezoelectric layer (70), and having a plurality of active portions (311, 312, 313), the second electrode (62) and the third electrode (63) being provided from an edge portion of an area opposite to the recess (12) to an outer side than the recess, the first electrode (61) being formed between the second electrode (62) and the third electrode (63), and the fourth electrode (80) constituting a common electrode of the plurality of active portions (311, 312, 313).

Description

Technical Field

[0001] This invention relates to a piezoelectric device with a piezoelectric actuator, a liquid ejector head that ejects liquid from a nozzle, and a liquid ejection device, and particularly to an inkjet recording head and an inkjet recording device that ejects ink as a liquid. Background Technology

[0002] Regarding liquid ejection heads as electronic devices, an inkjet recording head is known. The inkjet recording head includes: a substrate on which a pressure chamber communicating with a nozzle is disposed; a vibrating plate disposed on one side of the substrate; and a piezoelectric actuator having a piezoelectric layer disposed on the vibrating plate, and the ink in the pressure chamber is pressure-changed by the piezoelectric actuator to eject ink droplets from the nozzle (for example, see Patent Document 1).

[0003] However, there is a problem that the piezoelectric actuator has a residual strain that accumulates in the piezoelectric material layer due to repeated driving, which leads to a decrease in the displacement of the piezoelectric actuator.

[0004] Furthermore, this problem is not limited to liquid ejection heads, such as inkjet recorders, but also exists in other piezoelectric devices.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2010-208204 Summary of the Invention

[0006] The present invention, which solves the above-mentioned problems, is a piezoelectric device characterized by comprising: a substrate having a plurality of recesses arranged in a first direction; a vibrating plate; and a piezoelectric actuator having a first electrode, a second electrode, a third electrode, and a fourth electrode stacked sequentially, wherein a piezoelectric body layer is provided between the first electrode and the fourth electrode, between the second electrode and the fourth electrode, and between the third electrode and the fourth electrode; having a plurality of active portions sandwiched between the first electrode, the second electrode, the third electrode, and the fourth electrode; wherein the second electrode and the third electrode are disposed at both ends of the recesses in the first direction, extending from the edge of the region opposite the recess to a location further outward than the recess when viewed along the stacking direction; the first electrode is formed between the second electrode and the third electrode in the first direction; and the second electrode constitutes a common electrode for the plurality of active portions.

[0007] Furthermore, another aspect of the present invention is a liquid jet head, characterized by comprising: a substrate having a pressure chamber arranged in a first direction and communicating with a nozzle for jetting liquid; a vibrating plate; and a piezoelectric actuator having a first electrode, a second electrode, a third electrode, and a fourth electrode stacked sequentially, wherein a piezoelectric layer is provided between the first electrode and the fourth electrode, between the second electrode and the fourth electrode, and between the third electrode and the fourth electrode; having a plurality of active portions sandwiched between the first electrode, the second electrode, the third electrode, and the fourth electrode; wherein the second electrode and the third electrode are provided at both ends of the pressure chamber in the first direction, extending from the edge of the region opposite the pressure chamber to a location further outward than the pressure chamber when viewed along the stacking direction; the first electrode is formed between the second electrode and the third electrode in the first direction; and the fourth electrode constitutes a common electrode for the plurality of active portions.

[0008] In addition, another aspect of the present invention is a liquid injection device, characterized in that it includes a liquid injection head as described above.

[0009] Furthermore, another aspect of the present invention is a liquid jetting device, characterized by comprising: a substrate having a plurality of pressure chambers arranged in a first direction and communicating with nozzles for jetting liquid; a vibrating plate; a piezoelectric actuator having a first electrode, a second electrode, a third electrode, and a fourth electrode stacked sequentially, and having a piezoelectric layer between the first electrode and the fourth electrode, between the second electrode and the fourth electrode, and between the third electrode and the fourth electrode; a control unit for driving the piezoelectric actuator, having a plurality of active portions having the piezoelectric layer sandwiched between the first electrode, the second electrode, the third electrode, and the fourth electrode, wherein the second electrode and the third electrode are located at both ends of the pressure chamber in the first direction, along the stacking direction. During observation, the nozzle extends from the edge of the region opposite the pressure chamber to a location further outward than the pressure chamber. The first electrode is formed in the first direction between the second and third electrodes. The fourth electrode constitutes a common electrode for a plurality of active parts. The first electrode constitutes a separate electrode independently provided for each active part. The control unit performs the following operation: when the piezoelectric actuator is deformed toward the pressure chamber side, a first injection pulse is supplied to the first electrode and driven; when the piezoelectric actuator is deformed toward the side opposite to the pressure chamber, a second injection pulse is supplied to the second and third electrodes and driven; and liquid is ejected from the nozzle by the first and second injection pulses. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of an inkjet recording device.

[0011] Figure 2 This is an exploded perspective view of the recording head according to Embodiment 1.

[0012] Figure 3 This is a top view of the flow channel forming substrate according to Embodiment 1.

[0013] Figure 4 This is an enlarged top view of the main part of the flow channel forming substrate according to Embodiment 1.

[0014] Figure 5 This is a cross-sectional view of the recording head according to Embodiment 1.

[0015] Figure 6 This is a cross-sectional view of the main part of the recording head according to Embodiment 1.

[0016] Figure 7 A block diagram illustrating the electrical structure of an inkjet recording device.

[0017] Figure 8 The driving waveforms are the bias potential, the first driving signal, and the second driving signal.

[0018] Figure 9 A cross-sectional view illustrating the deformation state of the piezoelectric actuator and the vibrating plate.

[0019] Figure 10 A cross-sectional view illustrating the deformation state of the piezoelectric actuator and the vibrating plate.

[0020] Figure 11 A cross-sectional view illustrating the deformation state of the piezoelectric actuator and the vibrating plate.

[0021] Figure 12 A cross-sectional view illustrating the deformation state of the piezoelectric actuator and the vibrating plate.

[0022] Figure 13 A cross-sectional view illustrating the deformation state of the piezoelectric actuator and the vibrating plate.

[0023] Figure 14 The driving waveforms are the bias potential, the first driving signal, and the third driving signal.

[0024] Figure 15 The driving waveforms are a variation of the bias potential, the first driving signal, and the second driving signal.

[0025] Figure 16 This is a top view showing an enlarged view of the main part of the flow channel forming substrate involved in Embodiment 2.

[0026] Figure 17 This is a cross-sectional view of the main part of the recording head according to Embodiment 2.

[0027] Figure 18 These are the driving waveforms for the bias potential, the fourth driving signal, and the fifth driving signal.

[0028] Figure 19 A cross-sectional view illustrating the deformation state of the piezoelectric actuator and the vibrating plate.

[0029] Figure 20 A cross-sectional view illustrating the deformation state of the piezoelectric actuator and the vibrating plate.

[0030] Figure 21 A cross-sectional view illustrating the deformation state of the piezoelectric actuator and the vibrating plate.

[0031] Figure 22 This is an enlarged top view of the main part of the flow channel forming substrate of the modified example according to Embodiment 2.

[0032] Figure 23 The driving waveforms are variations of the bias potential, the fourth driving signal, and the fifth driving signal.

[0033] Figure 24 The driving waveforms are variations of the bias potential, the fourth driving signal, and the fifth driving signal.

[0034] Figure 25 A cross-sectional view of the main parts of the recording head as described in other embodiments.

[0035] Figure 26 A cross-sectional view of the main parts of the recording head as described in other embodiments.

[0036] Figure 27 A cross-sectional view of the main parts of the recording head as described in other embodiments.

[0037] Figure 28 A cross-sectional view of the main parts of the recording head as described in other embodiments.

[0038] Figure 29 A cross-sectional view of the main parts of the recording head as described in other embodiments.

[0039] Figure 30 An enlarged top view of the main portion of the flow channel forming substrate involved in other embodiments. Detailed Implementation

[0040] The present invention will now be described in detail based on embodiments. However, the following description illustrates one aspect of the invention, and any modifications can be made within the scope of the invention. Components marked with the same symbols in the various figures represent the same components, and descriptions may be omitted as appropriate. Furthermore, in the figures, X, Y, and Z represent three mutually orthogonal spatial axes. In this specification, the directions along these axes will be designated as the X direction, Y direction, and Z direction. The direction in which the arrow marks point in each figure will be designated as the positive (+) direction, and the opposite direction of the arrow marks as the negative (-) direction. Furthermore, regarding the three spatial axes X, Y, and Z, which are not limited to positive and negative directions, they will be described as the X-axis, Y-axis, and Z-axis. Furthermore, in the following embodiments, as an example, the "first direction" will be designated as the +X direction, and the "second direction" will be designated as the +Y direction. Furthermore, the "stack direction" will be designated as the -Z direction. However, the description of the structure in the stack direction will be based on the figure viewed along the +Z direction.

[0041] Implementation Method 1

[0042] Figure 1 The figure illustrates an inkjet recording device 1, which is an example of a liquid jetting device according to Embodiment 1 of the present invention.

[0043] like Figure 1 As shown, an inkjet recording device 1, as an example of a liquid jetting device, is a printing apparatus that jets ink, a type of liquid, as ink droplets onto a medium S such as printing paper, and prints images or the like by arranging the dots formed on the medium S. Furthermore, any material can be used as the medium S.

[0044] In the following text, the movement direction of the recording head 2, which will be described later, is defined as the X-axis, the transport direction of the medium S, which is orthogonal to the movement direction, is defined as the Y-axis, the surface parallel to the nozzle surface of the recording head 2 on which the nozzle 21 is formed is defined as the XY plane, and the direction intersecting the nozzle surface, i.e., the XY plane, which in this embodiment is orthogonal to the XY plane, is defined as the Z-axis, and the ink droplets are ejected along the +Z direction of the Z-axis.

[0045] The inkjet recording device 1 includes a liquid container 3, a conveying mechanism 4 for conveying the medium S, a control device 5, a moving mechanism 6, and a recording head 2.

[0046] The liquid container 3 stores the various types of ink ejected from the recording head 2 individually. Examples of liquid containers 3 include, for example, a detachable cartridge relative to the inkjet recording device 1, a bag-shaped ink bag formed of a flexible membrane, and an ink canister capable of being refilled with ink.

[0047] The details are described below. The control device 5 is configured to include, for example, a control processing unit such as a CPU (Central Processing Unit) or FPGA (Field Programmable Gate Array) and a storage device such as a semiconductor memory, and comprehensively controls the conveying mechanism 4, the moving mechanism 6, the recording head 2, etc.

[0048] The conveying mechanism 4 is a mechanism controlled by the control device 5 that conveys the medium S along the Y-axis, for example having a conveying roller 4a.

[0049] The moving mechanism 6 is controlled by the control device 5, causing the recording head 2 to reciprocate along the X-axis in the +X and -X directions. Specifically, the moving mechanism 6 in this embodiment includes a conveyor body 7 and a conveyor belt 8. The conveyor body 7 is a generally box-shaped structure, i.e., a carriage, that houses the recording head 2, and is fixed to the conveyor belt 8. The conveyor belt 8 is a seamless belt that runs along the X-axis. Under the control of the control device 5, the conveyor belt 8 rotates, thereby causing the recording head 2 and the conveyor body 7 to reciprocate along guide rails (not shown) in the +X and -X directions. Alternatively, a liquid container 3 can also be mounted on the conveyor body 7 along with the recording head 2.

[0050] Under the control of the control device 5, the recording head 2 sprays ink supplied from the liquid container 3 as ink droplets from multiple nozzles 21 onto the medium S in the +Z direction. By simultaneously spraying ink droplets from the recording head 2, conveying the medium S by the conveying mechanism 4, and reciprocating the recording head 2 by the moving mechanism 6, an image composed of ink is formed on the surface of the medium S, i.e., printing is performed.

[0051] Figure 2 An exploded perspective view of the recording head 2, which is an example of a liquid injection head in this embodiment. Figure 3 This is a top view of the flow channel forming substrate 10 of the recording head 2 as observed along the +Z direction. Figure 4 This is a top view showing an enlarged view of the main part of the flow channel forming substrate 10 of the recording head 2. Figure 5 For Figure 3 The cross-sectional view of record head 2 with reference to line A-A'. Figure 6 For Figure 4 The cross-sectional view of record head 2 with reference to line B-B'.

[0052] As shown in the figure, the recording head 2 of this embodiment includes a flow channel forming substrate 10, which is an example of a "substrate". The flow channel forming substrate 10 is made of a silicon substrate.

[0053] On the flow channel forming substrate 10, a plurality of pressure chambers 12 are arranged along a first direction, namely the +X direction. The pressure chambers 12 are formed such that, when viewed along the -Z direction, the +X direction is the short side direction and the +Y direction is the long side direction. Although in this embodiment the pressure chambers 12 have a rectangular shape when viewed along the -Z direction, this is not particularly limited; they may also be parallelogram-shaped, or a so-called rounded rectangle shape (also known as a racetrack shape) with semicircular ends along the long side, or even a polygonal shape. The plurality of pressure chambers 12 are arranged in a straight line along the +X direction such that their positions in the +Y direction are the same. The pressure chambers 12 adjacent to each other in the +X direction are separated by partitions 11. Of course, the arrangement of the pressure chambers 12 is not particularly limited. Figure 3 Examples.

[0054] Furthermore, the shape of the pressure chamber 12 observed along the +Z direction in this embodiment can be a rectangular shape, a parallelogram shape, a so-called rounded rectangle shape with semi-circular ends along the long side, an elliptical or oval shape, a circular shape, a polygonal shape, etc. In this embodiment, the pressure chamber 12 has a short side direction in the +X direction and a long side direction in the +Y direction. By arranging the pressure chambers 12 side by side in the short side direction, i.e., the +X direction, a high-density arrangement of the pressure chambers 12 can be achieved. This pressure chamber 12 corresponds to a "recess" provided on the "substrate".

[0055] A connecting plate 15 and a nozzle plate 20 are sequentially stacked on the +Z direction side of the flow channel forming substrate 10. Here, "stacked A and B" means that it also includes the case where there are other layers between A and B.

[0056] A nozzle connecting channel 16 is provided on the connecting plate 15, which connects the pressure chamber 12 and the nozzle 21.

[0057] Furthermore, a first manifold portion 17 and a second manifold portion 18, forming part of a manifold 100, are provided on the connecting plate 15. This manifold 100 serves as a common liquid chamber shared and connected by a plurality of pressure chambers 12. The first manifold portion 17 is provided to penetrate the connecting plate 15 in the +Z direction. Furthermore, the second manifold portion 18 is provided to have an opening on its surface in the +Z direction side, rather than penetrating the connecting plate 15 in the +Z direction.

[0058] Furthermore, on the connecting plate 15, a supply connecting channel 19 is independently provided for each pressure chamber 12, communicating with one end of the pressure chamber 12 along the Y-axis. The supply connecting channel 19 connects the second manifold section 18 and the pressure chamber 12, and supplies ink from the manifold 100 to the pressure chamber 12.

[0059] The nozzle plate 20 is disposed on the side of the connecting plate 15 opposite to the flow channel forming substrate 10, i.e., the +Z direction side.

[0060] Nozzles 21, which communicate with each pressure chamber 12 via nozzle communication channels 16, are formed on the nozzle plate 20. In this embodiment, two rows of nozzles 21 are arranged in a row along the +X direction and separated in the +Y direction. The nozzle plate 20 can be made of silicon substrates, glass substrates, SOI substrates, various ceramic substrates, metal substrates such as stainless steel substrates, or organic materials such as polyimide resin. The surface of the nozzle plate 20 with openings in the -Z direction of the nozzles 21 forms the liquid jetting surface 20a.

[0061] A vibrating plate 50 and a piezoelectric actuator 300 are sequentially stacked on the -Z direction side of the flow channel forming substrate 10. That is, the flow channel forming substrate 10, the vibrating plate 50, and the piezoelectric actuator 300 are sequentially stacked facing the -Z direction. Details about the vibrating plate 50 and the piezoelectric actuator 300 are described below.

[0062] On the surface of the flow channel forming substrate 10 in the -Z direction, such as Figure 2 as well as Figure 5 As shown, a protective substrate 30 having approximately the same size as the flow channel forming substrate 10 is joined. The protective substrate 30 has a space, namely a holding portion 31, for protecting the piezoelectric actuator 300. Furthermore, a through hole 32 extending in the +Z direction is provided between two holding portions 31 arranged side by side in the +Y direction on the protective substrate 30. The ends of the first individual lead electrode 91, the first common lead electrode 92, and the second common lead electrode 93, which are led out from the electrodes of the piezoelectric actuator 300, extend out of the through hole 32. The first individual lead electrode 91, the first common lead electrode 92, and the second common lead electrode 93 are electrically connected to the wiring substrate 120 connected to the control device 5 within the through hole 32.

[0063] In addition, such as Figure 5As shown, a housing component 40 is fixed on the protective substrate 30. This housing component 40, together with the flow channel forming substrate 10, defines a manifold 100 communicating with a plurality of pressure chambers 12. The housing component 40, when viewed from above in the +Z direction, has a shape substantially the same as the aforementioned connecting plate 15, and is engaged with both the protective substrate 30 and the connecting plate 15. In this embodiment, the housing component 40 is engaged with the connecting plate 15.

[0064] A third manifold portion 42 communicating with the first manifold portion 17 is provided on the housing component 40. The third manifold portion 42 has a concave shape with an opening in the +Z direction. Moreover, the manifold 100 of this embodiment is constituted by the first manifold portion 17 and the second manifold portion 18 provided on the connecting plate 15 and the third manifold portion 42 provided on the housing component 40. The manifolds 100 are continuously provided in the +X direction in which the pressure chambers 12 are arranged side by side. In addition, an inlet port 44 communicating with the manifolds 100 and used to supply ink to each manifold 100 is provided on the housing component 40. In addition, a connection port 43 communicating with the through hole 32 of the protective substrate 30 (described in detail later) and through which the wiring board 120 is inserted is provided on the housing component 40.

[0065] Furthermore, a malleable substrate 45 is provided on the +Z direction side of the openings of the first manifold portion 17 and the second manifold portion 18 of the connecting plate 15. This malleable substrate 45 seals the openings on the liquid injection surface 20a side of the first manifold portion 17 and the second manifold portion 18. In this embodiment, such a malleable substrate 45 includes a sealing film 46 made of a flexible thin film and a fixing substrate 47 made of a rigid material such as metal. Since the area of ​​the fixing substrate 47 opposite to the manifold 100 becomes an opening 48 that is completely removed in the thickness direction, one side of the manifold 100 becomes a flexible portion, or malleable portion 49, sealed only by the flexible sealing film 46.

[0066] The vibrating plate 50 and the piezoelectric actuator 300 of this embodiment will be described.

[0067] like Figure 5 as well as Figure 6As shown, the vibrating plate 50 is a component disposed in the -Z direction of the flow channel forming substrate 10, and has an elastic film 51 made of silicon oxide disposed on the flow channel forming substrate 10 side and an insulating film 52 made of zirconium oxide disposed on the -Z direction side of the elastic film 51. Alternatively, the elastic film 51 may be made of a substrate integral with the flow channel forming substrate 10; in such a structure, it is sometimes described as a "stack". The flow channels, such as the pressure chamber 12, are formed by anisotropic etching of the flow channel forming substrate 10, and the -Z direction surface of the pressure chamber 12 is defined by the elastic film 51. In this embodiment, the vibrating plate 50 is provided as a stack of the elastic film 51 and the insulating film 52, but it is not particularly limited to this.

[0068] like Figures 4 to 6 As shown, the piezoelectric actuator 300 is also called a piezoelectric element and serves as a pressure generating unit that causes pressure changes in the ink within the pressure chamber 12. The piezoelectric actuator 300 includes a first electrode 61, a second electrode 62, a third electrode 63, a fourth electrode 80, and a piezoelectric layer 70.

[0069] The first electrode 61, the second electrode 62, and the third electrode 63 are located in the +Z direction relative to the fourth electrode 80. That is, the fourth electrode 80 is located in the -Z direction relative to the first electrode 61, the second electrode 62, and the third electrode 63. In other words, the first electrode 61, the second electrode 62, and the third electrode 63, and the fourth electrode 80 are stacked sequentially in the -Z direction. Here, the stacking of the first electrode 61, the second electrode 62, and the third electrode 63, and the fourth electrode 80 means that, along the Z-axis, other layers are sandwiched between the first electrode 61, the second electrode 62, and the third electrode 63 and the fourth electrode 80. In this embodiment, the piezoelectric actuator 300 has a piezoelectric layer 70 between the first electrode 61 and the fourth electrode 80 along the Z-axis. Furthermore, the piezoelectric actuator 300 has a piezoelectric layer 70 between the second electrode 62 and the fourth electrode 80. Furthermore, the piezoelectric actuator 300 has a piezoelectric layer 70 between the third electrode 63 and the fourth electrode 80. However, the piezoelectric layer 70 is not present on the pressure chamber 12 side of the first electrode 61, i.e., in the +Z direction.

[0070] The first electrode 61, the second electrode 62, and the third electrode 63 are disposed on the surface of the vibrating plate 50 in the -Z direction. That is, the first electrode 61, the second electrode 62, and the third electrode 63 are disposed at the same position along the Z-axis.

[0071] The second electrode 62 and the third electrode 63 are disposed at both ends of the pressure chamber 12 in the +X direction, that is, at the ends in the +X direction and the -X direction, respectively, extending from the end of the region opposite to the pressure chamber 12 to the outside of the pressure chamber 12 when viewed in the -Z direction. In this embodiment, the second electrode 62 is disposed at the end of the pressure chamber 12 in the -X direction, extending from the edge of the region opposite to the pressure chamber 12 to the partition wall 11 on the outside of the pressure chamber 12 in the -X direction when viewed in the -Z direction. The third electrode 63 is disposed at the end of the pressure chamber in the +X direction, extending from the edge of the region opposite to the pressure chamber 12 to the partition wall 11 on the outside of the pressure chamber 12 in the +X direction when viewed in the -Z direction.

[0072] The second electrode 62 and the third electrode 63, provided for a pressure chamber 12, are configured to be electrically conductive on the flow channel forming substrate 10. Specifically, the second electrode 62 and the third electrode 63 are electrically conductive via a common connecting portion 64 continuously provided in the +X direction, connected to one side of the pressure chamber 12 along the Y-axis. In this embodiment, the second electrode 62, the third electrode 63, and the common connecting portion 64 are continuously provided by patterning the same metal layer. Of course, the second electrode 62, the third electrode 63, and the common connecting portion 64 may also be composed of different layers. That is, the electrical conductivity of the second electrode 62 and the third electrode 63 on the flow channel forming substrate 10 also includes the case where the conductivity is achieved via other components. Furthermore, the second electrode 62 and the third electrode 63 are continuous on the flow channel forming substrate 10, including the case where the second electrode 62 and the third electrode 63 are directly continuous on the flow channel forming substrate 10, and the case where the second electrode 62 and the third electrode 63 are continuous on the vibrating plate 50 provided on the flow channel forming substrate 10. That is to say, the substrate includes the area directly above the substrate, as well as the area above indicating the state where other components are sandwiched in the middle.

[0073] Furthermore, the second electrode 62 and the third electrode 63 are not separated but continuously arranged on the partition wall 11 between adjacent pressure chambers 12 in the +X direction. That is, in two pressure chambers 12 arranged side-by-side in the +X direction, the third electrode 63 for one pressure chamber 12 and the second electrode 62 for the other pressure chamber 12 are not interrupted but continuously arranged on the partition wall 11 between the two pressure chambers 12. In this embodiment, the second electrode 62 and the third electrode 63 of the two pressure chambers 12 arranged in the +X direction are distinguished and named by the center of the partition wall 11 in the +X direction.

[0074] The first electrode 61 is disposed between the second electrode 62 and the third electrode 63 in the +X direction. Here, "the first electrode 61 is formed between the second electrode 62 and the third electrode 63 in the +X direction" means that the center of the first electrode 61 in the +X direction is positioned between the centers of the second electrode 62 and the third electrode 63 in the +X direction. In this embodiment, the first electrode 61, the second electrode 62, and the third electrode 63 are disposed on a flat surface in the -Z direction of the vibrating plate 50, thus being positioned at the same location in the -Z direction. Therefore, the first electrode 61, the second electrode 62, and the third electrode 63 are positioned so that they do not overlap when viewed along the -Z direction. That is, the first electrode 61 is disposed with a gap between it and the second electrode 62 in the +X direction, and is disposed with a gap between it and the third electrode 63 in the -X direction. Of course, if the first electrode 61, the second electrode 62, and the third electrode 63 are arranged at different positions in the -Z direction, the first electrode 61, the second electrode 62, and the third electrode 63 can also be arranged at positions that partially overlap when observed along the -Z direction.

[0075] The piezoelectric layer 70 is continuously disposed in the +X direction with a predetermined width in the +Y direction. That is, the piezoelectric layer 70 is continuously disposed on the first electrode 61, the second electrode 62, and the third electrode 63 in the +X direction. Furthermore, the piezoelectric layer 70 is continuously disposed without interruption in the +X direction relative to the plurality of pressure chambers 12. Additionally, the piezoelectric layer 70 is disposed with approximately the same thickness in the +X direction. Alternatively, recesses corresponding to each partition wall 11 may be formed on the piezoelectric layer 70. The width of the recess in the +X direction only needs to be narrower than the width of the partition wall 11. Furthermore, the recess may be configured to penetrate the piezoelectric layer 70 in the thickness direction, i.e., the +Z direction, or it may be configured to extend to the middle of the thickness of the piezoelectric layer 70. That is, the piezoelectric layer 70 may be completely removed from the bottom surface of the recess in the +Z direction, or a portion of the piezoelectric layer 70 may remain.

[0076] The nozzle 21 side of the piezoelectric layer 70 is located further outward than the pressure chamber 12 and is formed with a length shorter than the end of the first electrode 61. Furthermore, the end of the nozzle 21 side of the first electrode 61 is not covered by the piezoelectric layer 70.

[0077] Furthermore, the side of the piezoelectric layer 70 opposite to the nozzle 21 on the Y-axis is further outward than the pressure chamber 12, and is formed with a length shorter than the ends of the second electrode 62 and the third electrode 63. The ends of the second electrode 62 and the third electrode 63 opposite to the nozzle 21, that is, the parts that communicate with the common communication portion 64, are not covered by the piezoelectric layer 70.

[0078] Such a piezoelectric layer 70 is constructed using a piezoelectric material made of a composite oxide with a perovskite structure represented by the general formula ABO3. As the perovskite-structured composite oxide used for the piezoelectric layer 70, lead-based piezoelectric materials containing lead or lead-free non-lead piezoelectric materials can be used. In this embodiment, lead zirconate titanate (PZT) is used as the piezoelectric layer 70.

[0079] A fourth electrode 80 is disposed on the -Z direction side surface of the piezoelectric layer 70. When observed along the +Z direction, the fourth electrode 80 covers the pressure chamber 12 in the +X direction. That is, when observed along the +Z direction, the fourth electrode 80 is positioned at a location overlapping the pressure chamber 12 in the +X direction. In this embodiment, the fourth electrode 80 is continuously disposed across the -Z direction side surface of the piezoelectric layer 70. That is, the fourth electrode 80 is continuously disposed such that, when observed along the +Z direction, it includes positions overlapping with the first electrode 61, the second electrode 62, and the third electrode 63. In other words, the piezoelectric layer 70 is formed between the first electrode 61 and the fourth electrode 80, between the second electrode 62 and the fourth electrode 80, and between the third electrode 63 and the fourth electrode 80. Furthermore, in this embodiment, since the first electrode 61, the second electrode 62, and the third electrode 63 are arranged at the same position in the +Z direction, the distance between the first electrode 61 and the fourth electrode 80 is the same as the distance between the second electrode 62 and the third electrode and the fourth electrode 80 in the +Z direction.

[0080] Regarding such a piezoelectric actuator 300, the portion that is sandwiched between the two opposing electrodes and generates piezoelectric strain in the piezoelectric layer 70 when a voltage is applied between them is called an active portion. In this embodiment, the portion sandwiched between the first electrode 61 and the fourth electrode 80 is called the first active portion 311, the portion sandwiched between the second electrode 62 and the fourth electrode 80 is called the second active portion 312, and the portion sandwiched between the third electrode 63 and the fourth electrode 80 is called the third active portion 313. That is, a total of three active portions are provided for each pressure chamber 12: one first active portion 311, one second active portion 312, and one third active portion 313. Furthermore, in two adjacent pressure chambers 12 in the +X direction, the second electrode 62 provided for one pressure chamber 12 and the third electrode 63 provided for the other pressure chamber 12 are continuous; therefore, the second active portion 312 provided for one pressure chamber 12 and the third active portion 313 provided for the other pressure chamber 12 are continuous. In this embodiment, the second active part 312 and the third active part 313 of the two pressure chambers 12 arranged in the +X direction are distinguished and named by the position that distinguishes the second electrode 62 and the third electrode 63, that is, the center of the partition wall 11 in the +X direction.

[0081] The first electrode 61 is individually separated for each pressure chamber 12, thus forming a separate electrode independently provided for each active part. Here, "the first electrode 61 is a separate electrode for each active part" means that the multiple first electrodes 61 provided on the multiple first active parts 311 on the flow channel forming substrate 10 are not electrically connected to each other, but are independently provided. Furthermore, the flow channel forming substrate 10 includes, as described above, the area directly above the flow channel forming substrate 10, as well as the area above where other components such as the vibrating plate 50 are sandwiched in the middle.

[0082] The second electrode 62 and the third electrode 63 constitute a common electrode for multiple active portions. Here, "the second electrode 62 is a common electrode for multiple active portions" means that the multiple second electrodes 62 disposed on multiple second active portions 312 are electrically connected to each other on the flow channel forming substrate 10. Similarly, "the third electrode 63 is a common electrode for multiple active portions" means that the multiple third electrodes 63 disposed on multiple third active portions 313 are electrically connected to each other on the flow channel forming substrate 10. In this embodiment, the second electrode 62 and the third electrode 63 refer to electrodes shared for the second active portions 312 and the third active portions 313 corresponding to one pressure chamber 12. Therefore, both the second electrode 62 and the third electrode 63 become common electrodes shared for the multiple second active portions 312 and the multiple third active portions 313 corresponding to the multiple pressure chambers 12.

[0083] Thus, by setting the second electrode 62 and the third electrode 63 as common electrodes for the multiple second active parts 312 and the multiple third active parts 313, it is not necessary to divide the space between the second electrode 62 and the third electrode 63 on the partition wall 11, thereby enabling the pressure chamber 12 to be arranged with high density in the +X direction. Furthermore, since it is not necessary to separately lead out wiring from the second electrode 62 and the third electrode 63 on the flow channel forming substrate 10, it is not necessary to have space for wiring and routing, thereby enabling the recording head 2 to be miniaturized.

[0084] The fourth electrode 80 constitutes a common electrode shared by multiple active parts. Here, the fourth electrode 80 being a common electrode for multiple active parts means that the fourth electrode 80 is configured to be shared by all active parts, namely, multiple first active parts 311, multiple second active parts 312, and multiple third active parts 313.

[0085] The portion of the piezoelectric actuator 300 that is opposite the pressure chamber 12 in the direction along the Z-axis is a flexible portion, and the outer portion of the pressure chamber 12 is a non-flexible portion.

[0086] In addition, such as Figure 4As shown, each first electrode 61 is connected to a first individual lead electrode 91 as a lead-out wiring. The first individual lead electrode 91 is led out to the flow channel forming substrate 10 such that one end is connected to one end of the first electrode 61 and the other end is arranged between two rows of pressure chambers 12 on the Y-axis. The first individual lead electrode 91 is provided independently for each of the first electrodes 61, and the first electrodes 61 are not electrically connected to each other.

[0087] In addition, such as Figure 3 as well as Figure 4 As shown, a first common lead electrode 92, serving as a lead-out wiring, is connected to the second electrode 62 and the third electrode 63. The first common lead electrode 92 is led out such that one end is connected to one end of the second electrode 62 and the third electrode 63, which are arranged side-by-side along the X-axis, and the other end is positioned between two rows of pressure chambers 12 on the Y-axis. Since the second electrode 62 and the third electrode 63 are arranged consecutively, the first common lead electrode 92 only needs to be connected to either the second electrode 62 or the third electrode 63.

[0088] like Figure 3 As shown, a second common lead electrode 93, serving as a lead-out wiring, is connected to the fourth electrode 80. The second common lead electrode 93 is led out in such a manner that one end is connected to one end of the fourth electrode 80 along the X-axis, and the other end is arranged between the two rows of pressure chambers 12 on the Y-axis.

[0089] A flexible wiring board 120 is connected to the ends of the first individual lead electrodes 91, the first common lead electrode 92, and the second common lead electrode 93 that are connected to the piezoelectric actuator 300. The wiring board 120 is equipped with a drive circuit 121 having switching elements for driving the piezoelectric actuator 300. The ends of the wiring board 120 opposite to the ends connected to the first individual lead electrodes 91, the first common lead electrode 92, and the second common lead electrode 93 are connected to a control device 5, and control signals from the control device 5 are supplied to the recording head 2 via the wiring board 120.

[0090] Here, refer to Figure 7 The control device 5 of this embodiment will be described. Furthermore, Figure 7 This is a block diagram illustrating the control structure of the inkjet recording device 1.

[0091] like Figure 7 As shown, the inkjet recording device 1 includes a control unit, namely a printer controller 210 and a printing engine 220, as described in this embodiment. The printer controller 210 is an element that controls the entire inkjet recording device 1, and in this embodiment, it is provided in the control device 5 provided on the inkjet recording device 1.

[0092] The printer controller 210 includes an external interface 211 (hereinafter referred to as external I / F 211), a RAM 212 for temporarily storing various data, a ROM 213 for storing control programs, and a control processing unit 214 including a CPU. Furthermore, the printer controller 210 includes: an oscillation circuit 215 that generates a clock signal; a drive signal generation unit 216 that generates drive signals for supplying to the recording head 2; and an internal interface 217 (hereinafter referred to as internal I / F 217) that sends drive signals, dot pattern data (bitmap data) expanded based on printing data, etc., to the print engine 220.

[0093] The external I / F 211 receives printing data, consisting of character codes, graphics functions, image data, etc., from an external device 230, such as a host computer. Furthermore, the external I / F 211 outputs a busy signal (BUSY) and an acknowledgment signal (ACK) to the external device 230.

[0094] RAM 212 functions as a receive buffer 212A, an intermediate buffer 212B, an output buffer 212C, and a working memory (not shown). Furthermore, the receive buffer 212A temporarily stores printing data received from the external I / F 211, the intermediate buffer 212B stores intermediate code data converted by the control processing unit 214, and the output buffer 212C stores dot pattern data. This dot pattern data is composed of printing data obtained by decoding (translating) grayscale data.

[0095] In addition, ROM213 stores not only control programs (control routines) used to implement various data processing, but also font data, graphics functions, etc.

[0096] The control processing unit 214 reads the printing data in the receive buffer 212A and stores the intermediate code data obtained by converting the printing data in the intermediate buffer 212B. Furthermore, it parses the intermediate code data read from the intermediate buffer 212B and expands it into dot pattern data by referring to font data and graphics functions stored in the ROM 213. Then, after performing the required decorative processing, the control processing unit 214 stores the expanded dot pattern data in the output buffer 212C.

[0097] Furthermore, if a line of dot pattern data is obtained in record head 2, the line of dot pattern data is output to record head 2 via internal I / F217.

[0098] The printing engine 220 is configured to include a recording head 2, a transport mechanism 4, and a moving mechanism 6. Since the transport mechanism 4 and the moving mechanism 6 have already been described above, a repetitive explanation is omitted.

[0099] The recording head 2 includes a drive circuit 121 and a piezoelectric actuator 300. The drive circuit 121 includes a shift register 122, a latch circuit 123, a level shifter 124, and a switch 125. These components generate an application pulse based on the drive signal generated by the drive signal generation unit 216. Here, the application pulse refers to the pulse that is actually applied to the piezoelectric actuator 300.

[0100] Here, the drive waveform representing the drive signal generated by the drive signal generation unit 216 will be explained. Furthermore, Figure 8 This represents the driving waveforms of the bias potential VBS, the first driving signal 201, and the second driving signal 202. Figures 9 to 13 A cross-sectional view along line B-B' to show the state in which the piezoelectric actuator 300 and the vibrating plate 50 are deformed by the drive signal.

[0101] like Figure 8 As shown, the drive signal generation unit 216 generates a first drive signal 201 and a second drive signal 202 as drive signals. The first drive signal 201 is supplied to the first electrode 61, and the second drive signal 202 is supplied to the second electrode 62 and the third electrode 63.

[0102] These first drive signals 201 and second drive signals 202 are repeatedly generated from the drive signal generation unit 216 at unit periods T defined by the clock signal oscillating from the oscillation circuit 215. The unit period T is also called the ejection period T or the recording period T, and corresponds to one pixel of an image or the like printed on the medium S. In this embodiment, the unit period T is divided into two periods: a first period T1 and a second period T2.

[0103] Furthermore, the first drive signal 201 is a signal that, within a first period T1 of a recording cycle T, drives the first active part 311 of the piezoelectric actuator 300 to eject ink droplets from the nozzle 21 in a manner that causes ink droplets to be ejected from the nozzle 21, and is repeatedly generated every recording cycle T. Moreover, during printing, when a dot pattern of one line (1 raster) is formed in the recording area of ​​the medium S, the ejection pulse DP of the first drive signal 201 is selectively supplied to the first active part 311 of the piezoelectric actuator 300 corresponding to each nozzle 21. That is, the control unit generates an application pulse for each first active part 311 corresponding to each nozzle 21 based on the head control signal and the first drive signal 201, and supplies the application pulse to the piezoelectric actuator 300.

[0104] The application pulse generated according to the first drive signal 201 is supplied to each individual electrode of the first active part 311, namely the first electrode 61. Furthermore, a bias potential vbs is supplied to the common electrode of the plurality of first active parts 311, namely the fourth electrode 80. Therefore, regarding the potential applied to the first electrode 61 by the application pulse, the bias potential vbs applied to the fourth electrode 80 becomes the reference potential. Additionally, the bias potential vbs supplied to the fourth electrode 80 corresponds to the "second potential" described in the technical solution. Furthermore, in this embodiment, the application pulse supplied to the first electrode 61 is explained using the first drive signal 201. Furthermore, each potential of the first drive signal 201 is described as the potential supplied to the first electrode 61. However, as described above, the voltage actually applied between the first electrode 61 and the fourth electrode 80 is the potential difference between the potential of the first drive signal 201 supplied to the first electrode 61 and the bias potential vbs supplied to the fourth electrode 80.

[0105] The jet pulse DP includes a first expansion element P1, a first expansion maintenance element P2, a first contraction element P3, a first contraction maintenance element P4, and a first recovery element P5. Furthermore, the application pulse generated according to the first drive signal 201 always supplies an intermediate potential, i.e., a first potential V1, to the first electrode 61 when the jet pulse DP is not supplied. Therefore, within a unit period T of the first drive signal 201, a first reference element B1 and a second reference element B2 supplying the first potential V1 are provided before and after the jet pulse DP. That is, the first drive signal 201 sequentially generates the first reference element B1, the jet pulse DP, and the second reference element B2 within a unit period T. Furthermore, the second reference element B2 is generated during a period including the second period T2.

[0106] Such first reference element B1 and second reference element B2 maintain the state in which the piezoelectric actuator 300 and the vibrating plate 50 flex and deform toward the pressure chamber 12, i.e., in the +Z direction, by continuously applying a first potential V1 greater than the bias potential vbs to the first electrode 61. Thus, the volume of the pressure chamber 12 is maintained at a first volume that is smaller than the reference volume. Furthermore, the deformation of the piezoelectric actuator 300 and the vibrating plate 50 toward the pressure chamber 12, i.e., in the +Z direction, refers to, in this embodiment, such as... Figure 9As shown, the surface of the piezoelectric actuator 300 on the pressure chamber 12 side, i.e., in the +Z direction, is deformed in a convex protrusion state. However, this also includes cases where, in the case where the initial deflection of the piezoelectric actuator 300 is such that it deforms in a convex protrusion towards the opposite side of the pressure chamber 12, i.e., the -Z side, the piezoelectric actuator 300 is deformed in a convex protrusion towards the -Z direction by means of the first reference element B1 and the second reference element B2, but the amount of protrusion in the -Z direction is reduced. In other words, the deformation of the piezoelectric actuator 300 and the vibrating plate towards the pressure chamber 12 side in the +Z direction also includes the state where the surface on the opposite side of the pressure chamber 12 side, i.e., the -Z side, is convexly protruding. In other words, the posture of the piezoelectric actuator 300, realized by the first reference element B1 and the second reference element B2, is determined by the magnitude of the first potential V1 based on the first reference element B1 and the second reference element B2, i.e., the displacement amount, which determines the characteristics of the laminated films including the vibrating plate 50 at the initial deflection of the piezoelectric actuator 300, i.e., the position of the internal stress or neutral line of each film and the displacement characteristics relative to the piezoelectric layer 70. Furthermore, the reference volume refers to the volume of the pressure chamber 12 in the state where no voltage is applied to the piezoelectric actuator 300, that is, in the state where the first active part 311, the second active part 312, and the third active part 313 are not driven.

[0107] The first expansion element P1 applies a potential to the first electrode 61 in a manner that ranges from a first potential V1 to a second potential V2, such as... Figure 10 As shown, the piezoelectric actuator 300 and the vibrating plate 50 are deformed in the -Z direction. As a result, the volume of the pressure chamber 12 expands from the first volume to the second volume, the meniscus of the ink in the nozzle 21 is introduced to the pressure chamber 12 side, and ink is supplied into the pressure chamber 12 from the manifold 100 side.

[0108] The first expansion sustaining element P2 continuously applies a second potential V2 to the first electrode 61, maintaining the volume of the pressure chamber 12, which has expanded through the first expansion element P1, at a second volume for a fixed time.

[0109] The first contraction element P3 applies a potential to the first electrode 61 in a manner that moves from the second potential V2 to the third potential V3, such as... Figure 11 As shown, the piezoelectric actuator 300 and the vibrating plate 50 are deformed in the +Z direction. As a result, the volume of the pressure chamber 12 is drastically reduced from the second volume to the third volume, thereby pressurizing the ink in the pressure chamber 12 and ejecting ink droplets from the nozzle 21.

[0110] The first shrinkage sustaining element P4 continuously applies a third potential V3 to the first electrode 61, maintaining the volume of the pressure chamber 12 at the third volume for a fixed time. During the period when the first shrinkage sustaining element P4 is supplied, the ink pressure in the pressure chamber 12, which is reduced due to the ejection of ink droplets, repeatedly rises and falls and decays through its inherent vibration.

[0111] The first recovery element P5 applies a potential to the first electrode 61 in a manner from the fourth potential V4 to the first potential V1, such as... Figure 12 As shown, the piezoelectric actuator 300 and the vibrating plate 50 are deformed in the -Z direction. As a result, the volume of the pressure chamber 12 expands from the third volume to the first volume and then recovers.

[0112] Subsequently, by continuously applying a first potential V1 to the first active part 311 using the second reference element B2, the volume of the pressure chamber 12 is maintained at a first volume that is reduced compared to the reference volume.

[0113] In such a first drive signal 201, for the first active part 311 of the piezoelectric actuator 300 that does not eject ink droplets, the ejection pulse DP is not supplied to the first electrode 61, but the first potential V1 of the first reference element B1 and the second reference element B2 is applied as an intermediate potential.

[0114] like Figure 8 As shown, the second drive signal 202 is repeatedly generated from the drive signal generation unit 216 every unit period T defined by the clock signal oscillating by the oscillation circuit 215. In this embodiment, the second drive signal is a signal that drives the second active part 312 and the third active part 313 of the piezoelectric actuator 300 in a manner that prevents ink droplets from being ejected from the nozzle 21 during a second period T2 within a recording period T, and is repeatedly generated every recording period T. Moreover, during printing, when a dot pattern of one line (1 raster) is formed in the recording area of ​​the medium S, the suppression pulse SVP of the second drive signal 202 is selectively applied to the second active part 312 and the third active part 313 of the piezoelectric actuator 300 corresponding to each nozzle 21. That is, the control unit generates an application pulse for the second active part 312 and the third active part 313 corresponding to each nozzle 21 based on the head control signal and the second drive signal 202, and supplies the application pulse to the piezoelectric actuator 300.

[0115] The application pulse generated according to the second drive signal 202 is supplied to the common electrodes of the plurality of second active parts 312 and the plurality of third active parts 313, namely the second electrode 62 and the third electrode 63. Furthermore, a bias potential vbs is supplied to the common electrode of the plurality of second active parts 312 and the plurality of third active parts 313, namely the fourth electrode 80, as described above. Therefore, regarding the potential applied to the second electrode 62 and the third electrode 63 by the application pulse, the bias potential vbs applied to the fourth electrode 80 becomes the reference potential. In this embodiment, the application pulse supplied to the second electrode 62 and the third electrode 63 is explained using the second drive signal 202. Furthermore, each potential of the second drive signal 202 is described as the potential supplied to the second electrode 62 and the third electrode 63. However, as described above, the voltage actually applied between the second electrode 62 and the third electrode 63 and the fourth electrode 80 is the potential difference between the potential of the second drive signal 202 supplied to the second electrode 62 and the third electrode 63 and the bias potential vbs supplied to the fourth electrode 80.

[0116] Here, the damping pulse SVP supplied to the second electrode 62 and the third electrode 63 includes a second expansion element P10, a second expansion maintenance element P11, and a second recovery element P12. Furthermore, the application pulse generated according to the second drive signal 202 always supplies an intermediate potential, i.e., a fourth potential V4, to the second electrode 62 and the third electrode 63 when the damping pulse SVP is not supplied. Therefore, within a unit period T of the second drive signal 202, a third reference element B3 and a fourth reference element B4 supplying the fourth potential V4 are provided before and after the damping pulse SVP. That is, the second drive signal 202 sequentially generates the third reference element B3, the damping pulse SVP, and the fourth reference element B4 within a unit period T. Furthermore, the third reference element B3 is generated during a period including the first period T1.

[0117] Such third reference element B3 and fourth reference element B4 supply the second electrode 62 and the third electrode 63 with a fourth potential V4 that is the same as the bias potential Vbs, thereby maintaining the state where the second active part 312 and the third active part 313 are not driven. The third reference element B3 is supplied during the first period T1 of driving the piezoelectric actuator 300 by the jet pulse DP. Therefore, when the ink droplets are ejected from the nozzle 21 by driving the first active part 311 by the jet pulse DP, the damping pulse SVP does not affect the ejection of the ink droplets realized by the jet pulse DP because the second active part 312 and the third active part 313 are not driven. In addition, since the third reference element B3 does not drive the second active part 312 and the third active part 313, the volume of the pressure chamber 12 is the same after the jet pulse DP, that is, it becomes the first volume realized by the second reference element B2.

[0118] The second expansion element P10, the second expansion maintenance element P11, and the second recovery element P12 are supplied to the second electrode 62 and the third electrode 63 during the second period T2, which is the period during which the second reference element B2 of the first drive signal 201 is supplied.

[0119] The second expansion element P10 applies a fifth potential V5 to the second electrode 62 and the third electrode 63, such as Figure 13 As shown, the piezoelectric actuator 300 and the vibrating plate 50 are deformed in the opposite direction to the pressure chamber 12, i.e., in the -Z direction. As a result, the volume of the pressure chamber 12 expands from the first volume to the fourth volume.

[0120] Furthermore, the second active part 312 and the third active part 313 are arranged such that, when viewed along the +Z direction, they extend from the area overlapping with the pressure chamber 12 to the area overlapping with the partition wall 11, that is, across the wall of the pressure chamber 12. Therefore, when the second active part 312 and the third active part 313 are driven, the piezoelectric actuator 300 and the vibrating plate 50 deform toward the opposite side of the pressure chamber 12, i.e., in the -Z direction. Moreover, the deformation of the piezoelectric actuator 300 and the vibrating plate 50 toward the opposite side of the pressure chamber 12, i.e., in the -Z direction, means, in this embodiment, as... Figure 13As shown, the piezoelectric actuator 300 deforms in a convex protrusion on the side opposite to the pressure chamber 12, i.e., in the -Z direction. However, this also includes cases where, during the initial deflection of the piezoelectric actuator 300 and the vibrating plate 50, in this embodiment, the piezoelectric actuator 300 and the vibrating plate 50 are deformed by the second reference element B2 in a manner that causes the surface in the +Z direction to convexly protrude. In other words, the second expansion element P10 maintains the piezoelectric actuator 300 and the vibrating plate 50 in a convex protrusion in the +Z direction, but deforms them in a manner that reduces the amount of protrusion in the +Z direction. That is, the deformation of the piezoelectric actuator 300 and the vibrating plate 50 in the side opposite to the pressure chamber 12, i.e., in the -Z direction, also includes maintaining the surface on the pressure chamber 12 side, i.e., in a convex protrusion in the +Z direction. The posture of the piezoelectric actuator 300 and the vibrating plate 50, realized by the second expansion element P10, is determined according to the posture of the piezoelectric actuator 300 in the second reference element B2 and the magnitude of the fifth potential V5, i.e., the displacement.

[0121] Furthermore, the fifth potential V5 of the second expansion element P10 is preferably set to the same potential as the first potential V1 of the first reference element B1 of the first drive signal 201 or the third potential V3 of the first contraction element P3. By setting the fifth potential V5 of the second expansion element P10 to the same potential as the first potential V1 of the first reference element B1 of the first drive signal 201 or the third potential V3 of the first contraction element P3, the circuit of the drive signal generation unit 216 can be simplified compared to the case where different potentials are generated.

[0122] The second expansion maintaining element P11 continuously applies a fifth potential V5 to the second electrode 62 and the third electrode 63, maintaining the volume of the pressure chamber 12, which has expanded through the second expansion element P10, at a fourth volume for a fixed time.

[0123] The second recovery element P12 applies a potential to the second electrode 62 and the third electrode 63 in a manner from the fifth potential V5 to the fourth potential V4, thereby deforming the piezoelectric actuator 300 and the vibrating plate 50 in the +Z direction. As a result, the volume of the pressure chamber 12 recovers from the fourth volume to the first volume.

[0124] Thus, by adding the second expansion element P10, the second expansion maintenance element P11, and the second recovery element P12 of the damping pulse SVP after the jetting pulse DP, the residual vibration of the ink in the pressure chamber 12 after ink is ejected from the nozzle 21 can be reduced in a short time. That is, when the second active part 312 and the third active part 313 of the piezoelectric actuator 300 are driven by the damping pulse SVP, as... Figure 13As shown, the second active portion 312 and the third active portion 313 contract along the Z-axis, and the piezoelectric actuator 300 and the vibrating plate 50 deform in a convex manner protruding towards the opposite side of the pressure chamber 12, i.e., in the -Z direction. At this time, tensile stress is applied to the portion including the first active portion 311 sandwiched between the second active portion 312 and the third active portion 313, thereby increasing the apparent Young's modulus. By increasing the apparent Young's modulus of the piezoelectric actuator 300, the residual vibration of the ink in the pressure chamber 12 after ink spraying can be converged in a short time.

[0125] Furthermore, by driving the second active portion 312 and the third active portion 313 of the piezoelectric actuator 300 with a damping pulse SVP, the piezoelectric actuator 300 is deformed in a convex manner protruding towards the pressure chamber 12 in the -Z direction, thereby eliminating residual strain in the piezoelectric layer 70. In other words, by repeatedly driving the piezoelectric actuator 300 with a jet pulse DP, the piezoelectric actuator 300 deforms repeatedly only in one direction, specifically in the direction protruding towards the pressure chamber 12 (i.e., the +Z direction) in this embodiment. Therefore, residual strain is generated in the piezoelectric layer 70, and it will not return to its original state even if the piezoelectric actuator 300 is not driven. Moreover, when the residual strain of the piezoelectric actuator 300 is large, the displacement of the piezoelectric actuator 300 decreases when it is driven, resulting in a reduction in jetting characteristics such as ink droplet weight and flight speed. In this embodiment, by driving the piezoelectric actuator 300 using the damping pulse SVP, the piezoelectric actuator 300 can be deformed in a direction different from the jetting pulse DP, that is, in a convex shape in the -Z direction. This eliminates residual strain in the piezoelectric layer 70, and even with repeated driving, the reduction in the displacement of the piezoelectric actuator 300 can be suppressed. Therefore, the reduction in the jetting characteristics of the ink droplets ejected from the nozzle 21 can be suppressed.

[0126] Since the second electrode 62 and the third electrode 63 are shared electrodes for multiple second active parts 312 and multiple third active parts 313, the second active parts 312 and third active parts 313 corresponding to the pressure chamber 12 connected to the nozzle 21 that does not eject ink droplets are also simultaneously driven by the damping pulse SVP. However, since the damping pulse SVP is a pulse that drives the piezoelectric actuator 300 in a manner that prevents ink droplets from being ejected, there is no particular problem even if the second active parts 312 and third active parts 313 corresponding to the nozzle 21 that does not eject ink droplets are driven by the damping pulse SVP. Furthermore, since the damping pulse SVP can also function as a so-called micro-vibration pulse, by using the damping pulse SVP to drive the second active parts 312 and third active parts 313 corresponding to the nozzle 21 that does not eject ink droplets, the ink near the nozzle 21 can be micro-vibrated. Therefore, the sedimentation of components contained in the ink near the pressure chamber 12 and nozzle 21 can be suppressed, and the retention of thickened ink can be suppressed, thereby suppressing poor ink droplet ejection caused by thickened ink. In other words, it is preferable that the damping pulse SVP is supplied to the second electrode 62 and the third electrode 63 corresponding to the pressure chamber 12 which is connected to the nozzle 21 that is not supplied with ejection pulse.

[0127] Furthermore, although the above structure is configured such that a bias potential Vbs is supplied to the fourth electrode 80, and a fifth potential V5, identical to the bias potential Vbs, is supplied to the second electrode 62 and the third electrode 63 via the third reference element B3 and the fourth reference element B4, it is not specifically limited to this configuration. For example, it is also possible to configure the fourth electrode 80 to be grounded (GND) instead of supplied with the bias potential Vbs, and to ground (GND) the fifth potential V5 of the third reference element B3 and the fourth reference element B4.

[0128] Here, refer to Figure 14 A variation of the control unit in this embodiment will be described. Furthermore, Figure 14 This represents the driving waveforms of the bias potential VBS, the first driving signal 201, and the third driving signal 203.

[0129] like Figure 14 As shown, a third drive signal 203 is supplied to the second electrode 62 and the third electrode 63. No damping pulse SVP is included in the third drive signal 203. Furthermore, the third drive signal 203 always supplies an intermediate potential, i.e., a sixth potential V6, to the second electrode 62 and the third electrode 63. In other words, the third drive signal 203 can also be considered to be composed of a fifth reference element B5 that supplies the sixth potential V6.

[0130] Here, the sixth potential V6 supplied to the second electrode 62 and the third electrode 63 is a different potential from the potential supplied to the fourth electrode 80, which in this embodiment is the bias potential Vbs. In this embodiment, the sixth potential V6 is preferably greater than the bias potential Vbs. That is, it is preferable that the relationship of sixth potential V6 > bias potential Vbs is satisfied. Thus, by setting the sixth potential V6 to a potential greater than the bias potential Vbs, it is possible to suppress the application of an electric field opposite to the jet pulse DP to the piezoelectric actuator 300. Therefore, it is possible to suppress the occurrence of cracks or damage in the piezoelectric actuator 300. Furthermore, this sixth potential V6 corresponds to the "first potential" in Embodiment 1. That is, in Figure 8 In the structure shown, the fourth potential V4 is the same as the bias potential vbs supplied to the fourth electrode 80. Figure 14 In the structure shown, the sixth potential V6 is greater than the "second potential," i.e., the bias potential Vbs. This satisfies... Figure 8 as well as Figure 14 The structural conditions of both electrodes satisfy the relationship that the potential supplied to the second electrode 62 and the third electrode 63 is greater than or equal to the bias potential vbs.

[0131] Furthermore, by consistently supplying a sixth potential V6 to the second electrode 62 and the third electrode 63 during the period when the jet pulse DP is supplied to the first electrode 61, the increase in residual strain generated when the piezoelectric actuator 300 is repeatedly driven by the jet pulse DP can be eliminated even without supplying the damping pulse SVP, thereby suppressing the displacement reduction caused by repeated driving. In addition, by maintaining the supply of the sixth potential V6 to the second electrode 62 and the third electrode 63, the natural vibration period Tc of the pressure chamber 12 can be adjusted. Here, there is an inverse relationship between the magnitude of the sixth potential V6 supplied to the second electrode 62 and the third electrode 63 and the magnitude of the natural vibration period Tc of the pressure chamber 12. Therefore, by supplying the sixth potential V6 to the second electrode 62 and the third electrode 63, the natural vibration period Tc of the pressure chamber 12 can be reduced, thereby enabling high-speed continuous jetting of ink droplets. Furthermore, in an inkjet recording apparatus 1 comprising a head unit that unitizes multiple recording heads 2, or multiple recording heads 2, even if there is a deviation in the inherent vibration period Tc between the multiple recording heads 2, the deviation in the inherent vibration period Tc between the multiple recording heads 2 can be reduced by changing the sixth potential V6 of each recording head 2. Therefore, deviations in the ejection characteristics such as ink weight and ejection velocity of the ink droplets ejected from the multiple recording heads 2 can be suppressed.

[0132] Furthermore, this structure, which always supplies a sixth potential V6 to the second electrode 62 and the third electrode 63 during the period of supplying the jet pulse DP to the first electrode 61, can also be applied to the second drive signal 202 with the damping pulse SVP. Here, in Figure 15 The diagram shows the structure in which the sixth potential V6 is applied in the second drive signal 202. Additionally, Figure 15 The driving waveforms represent a modified example of the bias potential VBS, the first driving signal 201, and the second driving signal 202.

[0133] like Figure 15 As shown, when the second driving signal 202 does not supply the damping pulse SVP, it always supplies an intermediate potential, namely the sixth potential V6, to the second electrode 62 and the third electrode 63. That is to say, the second driving signal 202 has a third reference element B3, a damping pulse SVP, and a fourth reference element B4. In the third reference element B3 and the fourth reference element B4, the sixth potential V6 is supplied to the second electrode 62 and the third electrode 63.

[0134] In the third reference element B3 and the fourth reference element B4, a sixth potential V6, greater than the bias potential vbs, is supplied to the second electrode 62 and the third electrode 63. That is, the third reference element B3 supplies the sixth potential V6 to the second electrode 62 and the third electrode 63 during the first period T1 of supplying the jet pulse DP to the first electrode 61. Therefore, the inherent vibration period Tc of the pressure chamber 12 during the supply of the jet pulse DP can be reduced, and the inherent vibration period Tc can be adjusted. Furthermore, since the second drive signal 202 has a damping pulse SVP, it can achieve the same effect as that achieved by the damping pulse SVP.

[0135] In addition, Figure 15 In the example shown, the waveform of the damping pulse SVP is set to be similar to... Figure 8 The same waveform is used, so the fourth potential V4 is set to a potential greater than the third potential V3, but it is not specifically limited to this; the fourth potential V4 can also be set to the same potential as the third potential V3. Therefore, compared with the case where the fourth potential V4 and the third potential V3 are different, the circuit of the drive signal generation unit 216 can be simplified.

[0136] As described above, the recording head 2, as an example of the piezoelectric device of the present invention, includes: a flow channel forming substrate 10, which is a substrate having recesses, i.e., pressure chambers 12, arranged in a first direction, i.e., the +X direction, communicating with nozzles 21 for jetting liquid; a vibrating plate 50; and a piezoelectric actuator 300. The piezoelectric actuator 300 sequentially includes: a first electrode 61; a second electrode 62 and a third electrode 63; and a fourth electrode 80. Furthermore, the piezoelectric actuator 300 has a piezoelectric layer 70 between the first electrode 61 and the fourth electrode 80, between the second electrode 62 and the fourth electrode 80, and between the third electrode 63 and the fourth electrode 80. In addition, it has a plurality of active portions, i.e., a first active portion 311, a second active portion 312, and a third active portion 313, which are sandwiched between the first electrode 61, the second electrode 62, the third electrode 63, and the fourth electrode 80, respectively. Furthermore, the second electrode 62 and the third electrode 63 are positioned at both ends of the pressure chamber 12 in the +X direction, extending from the edge of the region opposite the pressure chamber 12 to a position further outward than the pressure chamber 12 when viewed along the stacking direction, i.e., the -Z direction. Additionally, the first electrode 61 is formed between the second electrode 62 and the third electrode 63 in the +X direction, and the fourth electrode 80 constitutes a common electrode for multiple first active portions 311, second active portions 312, and third active portions 313.

[0137] Thus, by providing a first electrode 61 that drives the piezoelectric actuator 300 toward the pressure chamber 12, and a second electrode 62 and a third electrode 63 that drive the piezoelectric actuator 300 toward the opposite side of the pressure chamber 12, residual strain is less likely to occur in the piezoelectric layer 70, even with repeated driving of the piezoelectric actuator 300, compared to the case where the piezoelectric actuator 300 is only deformed in any one direction along the Z-axis. Therefore, even with repeated driving of the piezoelectric actuator 300, the reduction in displacement can be suppressed. Therefore, even with repeated driving of the piezoelectric actuator 300, the reduction in ejection characteristics such as ink weight of the ink droplets ejected from the nozzle 21 can be suppressed, thereby enabling continued high-quality printing. Furthermore, compared to the case where the piezoelectric actuator 300 is only driven in any one direction along the Z-axis, the displacement can be increased. Therefore, the weight of the ink droplets ejected from the nozzle 21 can be increased.

[0138] Furthermore, the recording head 2, as an example of the piezoelectric device of the present invention, includes: a flow channel forming substrate 10, which is a substrate having recesses, i.e., pressure chambers 12, formed in a first direction, i.e., the +X direction, communicating with nozzles 21 for jetting liquid; a vibrating plate 50; and a piezoelectric actuator 300. The piezoelectric actuator 300 sequentially includes: a first electrode 61; a second electrode 62 and a third electrode 63; and a fourth electrode 80. Furthermore, the piezoelectric actuator 300 has a piezoelectric layer 70 between the first electrode 61 and the fourth electrode 80, between the second electrode 62 and the fourth electrode 80, and between the third electrode 63 and the fourth electrode 80. In addition, it has a plurality of active portions, i.e., a first active portion 311, a second active portion 312, and a third active portion 313, which are sandwiched between the first electrode 61, the second electrode 62, the third electrode 63, and the fourth electrode 80, respectively. Furthermore, the second electrode 62 and the third electrode 63 are positioned at both ends of the pressure chamber 12 in the +X direction, extending from the edge of the region opposite the pressure chamber 12 to a position further outward than the pressure chamber 12 when viewed along the stacking direction, i.e., the -Z direction. Additionally, the first electrode 61 is formed between the second electrode 62 and the third electrode 63 in the +X direction. The second electrode 62, the third electrode 63, and the fourth electrode 80 constitute a common electrode for multiple first active portions 311, second active portions 312, and third active portions 313, while the first electrode 61 constitutes a separate electrode independently provided for each first active portion 311.

[0139] Thus, by providing a first electrode 61 that drives the piezoelectric actuator 300 to deform toward the pressure chamber 12, and a second electrode 62 and a third electrode 63 that drive the piezoelectric actuator 300 to deform toward the opposite side of the pressure chamber 12, the residual strain of the piezoelectric layer 70 during repeated driving of the piezoelectric actuator 300 can be reduced, thereby suppressing the reduction in displacement caused by repeated driving. Therefore, the reduction in ejection characteristics such as the weight and flight speed of the ink droplets ejected from the nozzle 21 during repeated driving of the piezoelectric actuator 300 can be suppressed.

[0140] Furthermore, since the second electrode 62 constitutes a common electrode for multiple second active portions 312, and the third electrode 63 constitutes a common electrode for multiple third active portions 313, the number of lead wires, i.e., the second common lead electrodes 93, drawn from these second electrodes 62 and third electrodes 63 can be reduced. Therefore, the wiring space of the wiring can be reduced, the area of ​​the XY plane of the flow channel forming substrate 10 can be reduced, thereby miniaturizing the recording head 2.

[0141] Furthermore, the piezoelectric layer 70 and the fourth electrode 80 do not need to be patterned in conjunction with the first electrode 61. That is, the piezoelectric layer 70 and the fourth electrode 80 can be formed with a substantially uniform thickness, spanning the first electrode 61, the second electrode 62, and the third electrode 63. Therefore, it is possible to suppress the deterioration of the piezoelectric layer 70 due to patterning, and to suppress the localized reduction of piezoelectric properties.

[0142] Furthermore, in the recording head 2 of this embodiment, it is preferable that the spacing between the first electrode 61 and the fourth electrode 80, and the spacing between the second electrode 62 and the third electrode 63 and the fourth electrode 80, are the same in the stacking direction, i.e., the -Z direction. This simplifies the structure, thereby reducing manufacturing steps and lowering costs. Additionally, because the spacing is the same, it is less likely to cause deviations in residual strain in the piezoelectric layer 70, which is also preferable.

[0143] Furthermore, in the recording head 2 of this embodiment, it is preferable that the piezoelectric layer 70 is not present on the recess of the first electrode 61, i.e., on the pressure chamber 12 side. Accordingly, without the piezoelectric layer 70 that increases the dielectric loss tangent tanδ on the pressure chamber 12 side of the first electrode 61, the heat generated by dielectric loss when driving the piezoelectric actuator 300 is difficult to generate, and therefore, the temperature of the ink in the pressure chamber 12 is difficult to rise.

[0144] Furthermore, in the recording head 2 of this embodiment, it is preferable that the first electrode 61, the second electrode 62, and the third electrode 63 do not overlap each other in the first direction, i.e., the +X direction, when observed along the stacking direction. This allows the first electrode 61, the second electrode 62, and the third electrode 63 to be non-conductive. Moreover, since the first electrode 61, the second electrode 62, and the third electrode 63 do not overlap in the +X direction, they can be formed at the same position in the -Z direction. Therefore, the first electrode 61, the second electrode 62, and the third electrode 63 can be formed simultaneously in the same layer, thereby reducing manufacturing processes and lowering costs.

[0145] Furthermore, in the recording head 2 of this embodiment, it is preferable that when the fourth electrode 80 observes along the stacking direction, i.e., the -Z direction, it covers the recess, i.e., the pressure chamber 12, in the first direction, i.e., the +X direction. Since the first electrode 61 and the piezoelectric layer 70 disposed in the -Z direction of the pressure chamber 12 are covered by the fourth electrode 80, the erosion of the piezoelectric layer 70 by moisture can be suppressed, thereby suppressing the shortening of the lifespan of the piezoelectric layer 70.

[0146] Furthermore, in the recording head 2 of this embodiment, it is preferable that when the recess, i.e., the pressure chamber 12, is observed along the stacking direction, i.e., the -Z direction, the second direction, i.e., the +Y direction, which is orthogonal to the first direction, i.e., the +X direction, becomes the long side direction. Accordingly, it is possible to arrange the pressure chambers 12 in a high density in the +X direction while ensuring the volume of the pressure chambers 12.

[0147] Furthermore, in the recording head 2 of this embodiment, the vibrating plate 50 preferably comprises zirconium oxide. When a lead-containing material is used as the piezoelectric layer 70, the diffusion of lead into the vibrating plate 50 can be suppressed.

[0148] Furthermore, the inkjet recording device 1, as an example of the liquid jetting apparatus of the present invention, includes the recording head 2 described above. This enables the inkjet recording device 1 to achieve a high level of reliability, where print quality is unlikely to deteriorate even with repeated printing.

[0149] Furthermore, as an example of the liquid jetting device of this embodiment, the inkjet recording device 1 includes: a flow channel forming substrate 10, which is a substrate having recesses, i.e., pressure chambers 12, formed in a first direction, i.e., the +X direction, communicating with nozzles 21 for jetting liquid; a vibrating plate 50; a piezoelectric actuator 300; and a control unit that drives the piezoelectric actuator 300. The piezoelectric actuator 300 sequentially includes: a first electrode 61; a second electrode 62 and a third electrode 63; and a fourth electrode 80. Furthermore, the piezoelectric actuator 300 has a piezoelectric layer 70 between the first electrode 61 and the fourth electrode 80, between the second electrode 62 and the fourth electrode 80, and between the third electrode 63 and the fourth electrode 80. In addition, it has a plurality of active portions, i.e., a first active portion 311, a second active portion 312, and a third active portion 313, which are sandwiched between the first electrode 61, the second electrode 62, the third electrode 63, and the fourth electrode 80, respectively. Furthermore, the second electrode 62 and the third electrode 63 are positioned at both ends of the pressure chamber 12 in the +X direction, extending from the edge of the region opposite the pressure chamber 12 to a position further outward than the pressure chamber 12 when viewed along the stacking direction, i.e., the -Z direction. Additionally, the first electrode 61 is formed between the second electrode 62 and the third electrode 63 in the +X direction. The second electrode 62, the third electrode 63, and the fourth electrode 80 constitute a common electrode for multiple first active parts 311, second active parts 312, and third active parts 313. The first electrode 61 constitutes a separate electrode independently provided for each first active part 311. Furthermore, the control unit supplies a jet pulse DP that causes liquid to be ejected from the nozzle 21 to the first electrode 61. At least after the jet pulse DP, the control unit supplies a damping pulse SVP that drives the piezoelectric actuator 300 to prevent liquid from being ejected from the nozzle 21 to the second electrode 62 and the third electrode 63.

[0150] Thus, when the ink droplets are ejected, the control unit supplies an ejection pulse DP to the first electrode 61, causing the piezoelectric actuator 300 to deform toward the pressure chamber 12. Furthermore, by supplying a damping pulse SVP after the ejection pulse DP, the piezoelectric actuator 300 deforms toward the opposite side of the pressure chamber 12. Therefore, even when ink droplets are repeatedly ejected using the ejection pulse DP, the increase in residual strain of the piezoelectric layer 70 can be suppressed by supplying the damping pulse SVP, thereby suppressing the decrease in displacement caused by repeated driving of the piezoelectric actuator 300. Furthermore, by adding the damping pulse SVP after the ejection pulse DP, the apparent Young's modulus of the piezoelectric layer 70 can be increased, causing the residual vibration after the ejection pulse DP to converge in a short time. Therefore, ink droplet ejection can be repeatedly performed in a short time, enabling high-speed continuous ejection. Furthermore, by supplying vibration damping pulses (SVP) to the second electrode 62 and the third electrode 63 corresponding to the pressure chamber 12 that does not eject ink droplets, the ink near the pressure chamber 12 and the nozzle 21 can be micro-vibrated, thereby suppressing the sedimentation of components contained in the ink, suppressing the retention of thickened ink, and further suppressing poor ink droplet ejection caused by thickened ink.

[0151] Furthermore, in the inkjet recording apparatus 1 of this embodiment, it is preferable that the control unit deforms the vibrating plate 50 in a manner that protrudes towards the opposite side of the pressure chamber 12 by means of a damping pulse SVP. In this way, by using the damping pulse SVP to deform the vibrating plate 50 in a manner that protrudes towards the opposite side of the pressure chamber 12, i.e., in the -Z direction, it is possible to reduce the residual strain of the piezoelectric layer 70 caused by repeated driving with jet pulse DP.

[0152] Furthermore, in the inkjet recording apparatus 1 of this embodiment, it is preferable that the control unit deforms the vibrating plate 50 in a manner that protrudes towards the pressure chamber 12 by means of an inkjet pulse DP. Accordingly, the driving efficiency of the piezoelectric actuator 300 can be improved, and the ink droplet ejection characteristics can be enhanced.

[0153] Furthermore, in the inkjet recording apparatus 1 of this embodiment, it is preferable that the control unit supplies a first drive signal 201, including an ejection pulse DP, to the first electrode 61, and during the period when the first drive signal 201 is supplied to the first electrode 61, a first potential, namely a sixth potential V6, which is different from the potential supplied to the fourth electrode 80, is supplied to the second electrode 62 and the third electrode 63. Accordingly, by maintaining the state of supplying the sixth potential V6 to the second electrode 62 and the third electrode 63 during the period when the first drive signal 201 is supplied to the first electrode 61, the inherent vibration period Tc of the pressure chamber 12 can be adjusted. Therefore, the inherent vibration period Tc of the pressure chamber 12 can be shortened, thereby enabling continuous ejection of ink droplets at high speed. In addition, in the inkjet recording apparatus 1 which has a head unit that unitizes multiple recording heads 2 or multiple recording heads 2, even if there is a deviation in the inherent vibration period Tc between the multiple recording heads 2, the deviation in the inherent vibration period Tc between the multiple recording heads 2 can be reduced by changing the sixth potential V6 of each recording head 2. Therefore, deviations in the ink ejection characteristics, such as ink weight and ejection speed, of the ink droplets ejected from the multiple recording heads 2 can be suppressed. Furthermore, although the example above specifies that a bias potential VBS is supplied to the fourth electrode 80, this is not a limitation; the fourth electrode 80 can also be grounded (GND).

[0154] Furthermore, in the inkjet recording device 1, which is an example of the liquid jetting device of this embodiment, the device includes: a flow channel forming substrate 10, which is a substrate having recesses, i.e., pressure chambers 12, formed in a first direction, i.e., the +X direction, communicating with nozzles 21 for jetting liquid; a vibrating plate 50; a piezoelectric actuator 300; and a control unit that drives the piezoelectric actuator 300. The piezoelectric actuator 300 sequentially includes: a first electrode 61; a second electrode 62 and a third electrode 63; and a fourth electrode 80. Furthermore, the piezoelectric actuator 300 has a piezoelectric layer 70 between the first electrode 61 and the fourth electrode 80, between the second electrode 62 and the fourth electrode 80, and between the third electrode 63 and the fourth electrode 80. In addition, it has a plurality of active parts, i.e., a first active part 311, a second active part 312, and a third active part 313, which are sandwiched between the first electrode 61, the second electrode 62, the third electrode 63, and the fourth electrode 80, respectively. Furthermore, the second electrode 62 and the third electrode 63 are positioned at both ends of the pressure chamber 12 in the +X direction, extending from the edge of the region opposite the pressure chamber 12 to a position further outward than the pressure chamber 12 when viewed along the stacking direction, i.e., the -Z direction. Additionally, the first electrode 61 is formed between the second electrode 62 and the third electrode 63 in the +X direction. The second electrode 62, the third electrode 63, and the fourth electrode 80 constitute a common electrode for multiple first active parts 311, second active parts 312, and third active parts 313. The first electrode 61 is a separate electrode independently provided for each first active part 311. Furthermore, the control unit supplies a first drive signal 201, including a jet pulse DP that causes liquid to be ejected from the nozzle 21, to the first electrode 61. During the period when the first drive signal 201 is supplied to the first electrode 61, the control unit supplies a first potential, i.e., a sixth potential V6, which is different from the potential supplied to the fourth electrode 80, to the second electrode 62 and the third electrode 63.

[0155] Accordingly, by maintaining the supply of the sixth potential V6 to the second electrode 62 and the third electrode 63 during the period when the first drive signal 201 is supplied to the first electrode 61, the inherent vibration period Tc of the pressure chamber 12 can be adjusted. Therefore, the inherent vibration period Tc of the pressure chamber 12 can be reduced, thereby enabling high-speed continuous ejection of ink droplets. Furthermore, in an inkjet recording device 1 comprising a head unit or multiple recording heads 2, even if there is a deviation in the inherent vibration period Tc between the multiple recording heads 2, the deviation in the inherent vibration period Tc between the multiple recording heads 2 can be reduced by changing the sixth potential V6 of each recording head 2. Therefore, deviations in the ejection characteristics such as ink weight and ejection speed of the ink droplets ejected from the multiple recording heads 2 can be suppressed. Additionally, although in the above example, the bias potential Vbs is supplied to the fourth electrode 80, this is not a particular limitation; the fourth electrode 80 can also be grounded (GND).

[0156] Furthermore, in the inkjet recording apparatus 1 of this embodiment, it is preferable that the control unit supplies a bias potential vbs, which is a second potential, to the fourth electrode 80 during the supply of the first drive signal 201, and that the sixth potential V6, which is a first potential, is above the bias potential vbs. Thus, by setting the sixth potential V6 to a potential greater than the bias potential vbs, it is possible to suppress the application of an electric field opposite to the jet pulse DP to the piezoelectric actuator 300. Therefore, it is possible to suppress the occurrence of cracks or damage in the piezoelectric actuator 300.

[0157] Implementation Method 2

[0158] Figure 16 This is a top view with an enlarged view of the main part when observing the flow channel forming substrate 10 of the recording head 2, which is an example of a liquid jetting head according to Embodiment 2 of the present invention, along the +Z direction. Figure 17 for Figure 16 A cross-sectional view along line C-C'. Additionally, components identical to those in the embodiments described above are labeled with the same symbols, and repeated descriptions are omitted.

[0159] As shown in the figure, the piezoelectric actuator 300 is designed for a pressure chamber 12 and includes a first electrode 61, a second electrode 62, a third electrode 63, a piezoelectric layer 70, and a fourth electrode 80.

[0160] The first electrode 61, the second electrode 62, and the third electrode 63 are located in the +Z direction relative to the fourth electrode 80. That is, the fourth electrode 80 is located in the -Z direction relative to the first electrode 61, the second electrode 62, and the third electrode 63. In other words, the first electrode 61, the second electrode 62, the third electrode 63, and the fourth electrode 80 are stacked sequentially in the -Z direction. Here, "stacked" means that in the Z-axis direction, there are other layers between the first electrode 61, the second electrode 62, the third electrode 63, and the fourth electrode 80. In this embodiment, the piezoelectric actuator 300 has a piezoelectric layer 70 between the first electrode 61 and the fourth electrode 80 in the Z-axis direction. Furthermore, the piezoelectric actuator 300 has a piezoelectric layer 70 between the second electrode 62 and the fourth electrode 80. Additionally, the piezoelectric actuator 300 has a piezoelectric layer 70 between the third electrode 63 and the fourth electrode 80.

[0161] The first electrode 61, the second electrode 62, and the third electrode 63 are disposed on the surface of the vibrating plate 50 in the -Z direction. That is, the first electrode 61, the second electrode 62, and the third electrode 63 are disposed at the same position along the Z-axis.

[0162] The second electrode 62 and the third electrode 63 are disposed at both ends of the pressure chamber 12 in the +X direction, that is, at the ends in the +X direction and the -X direction, respectively, extending from the end of the region opposite to the pressure chamber 12 to the outside of the pressure chamber 12 when viewed in the -Z direction. In this embodiment, the second electrode 62 is disposed at the end of the pressure chamber 12 in the -X direction, extending from the edge of the region opposite to the pressure chamber 12 to the partition wall 11 on the outside of the pressure chamber 12 in the -X direction when viewed in the -Z direction. The third electrode 63 is disposed at the end of the pressure chamber in the +X direction, extending from the edge of the region opposite to the pressure chamber 12 to the partition wall 11 on the outside of the pressure chamber 12 in the +X direction when viewed in the -Z direction.

[0163] The second electrode 62 and the third electrode 63 are divided for each pressure chamber 12, thus forming individual electrodes independently provided for each active part. Here, "individual electrodes for each active part" means that, in this embodiment, the multiple second electrodes 62 provided on the multiple second active parts 312 on the flow channel forming substrate 10 are not electrically connected to each other and are independently provided. Furthermore, "on the flow channel forming substrate 10" means including directly above the flow channel forming substrate 10 as described above, and also includes the state where other components such as the vibrating plate 50 are present in between. In addition, in the two pressure chambers 12 arranged in the +X direction, the second electrode 62 of one pressure chamber 12 and the third electrode 63 of the other pressure chamber 12 are arranged at intervals such that they are not connected to each other on the partition wall 11 that divides the two pressure chambers 12 in the +X direction.

[0164] Furthermore, in this embodiment, the second electrode 62 and the third electrode 63, which are provided for one pressure chamber 12, are electrically conductively disposed on the flow channel forming substrate 10. Specifically, the second electrode 62 and the third electrode 63 are connected to and electrically conductively disposed via a separate communication portion 64A, which is independently provided for each pressure chamber 12 on one side of the outer side of the pressure chamber 12 along the Y-axis. In this embodiment, the second electrode 62, the third electrode 63, and the separate communication portion 64A are continuously disposed by patterning the same metal layer. Of course, the second electrode 62, the third electrode 63, and the separate communication portion 64A may also be composed of different layers. That is, the electrical conductivity of the second electrode 62 and the third electrode 63 on the flow channel forming substrate 10 also includes the case where the conductivity is achieved via other components. Furthermore, the continuous placement of the second electrode 62 and the third electrode 63 on the flow channel forming substrate 10 corresponding to one pressure chamber 12 includes both the second electrode 62 and the third electrode 63 being directly above the flow channel forming substrate 10 and above it. Thus, by electrically connecting the second electrode 62 and the third electrode 63, which are respectively provided for one pressure chamber 12, it is not necessary to provide lead wires on the second electrode 62 and the third electrode 63, nor is it necessary to connect the terminals of the wiring board 120. Therefore, it is not necessary to have space for arranging wiring on the flow channel forming substrate 10 or space for connecting the wiring board 120, thereby enabling the miniaturization of the area of ​​the flow channel forming substrate 10 along the XY plane. However, by connecting the second electrode 62 and the third electrode 63, which are respectively provided for one pressure chamber 12, the second active part 312 and the third active part 313 cannot be driven individually, but are driven simultaneously. In addition, a lead wire, namely a second individual lead electrode 94, is connected to the individual communication part 64A. The second individual lead electrode 94 is arranged along the Y-axis such that one end is connected to the individual communication part 64A and the other end is arranged on the outside of the two rows of pressure chambers on the Y-axis. Therefore, although not specifically illustrated, the second individual lead electrode 94 is connected to another wiring substrate independent of the wiring substrate 120. Alternatively, the second individual lead electrode 94 could be led out from either the second electrode 62 or the third electrode 63 provided for a pressure chamber 12 in the same direction as the first individual lead electrode 91. Thus, by leading out the first individual lead electrode 91 and the second individual lead electrode 94 in the same direction, they can be connected to a wiring substrate 120. However, by leading out the first individual lead electrode 91 and the second individual lead electrode 94 in the same direction, there is a possibility that, in order to ensure space for wiring, the pressure chamber 12 cannot be densely arranged along the +X direction, resulting in the flow channel forming substrate 10 becoming larger in the +X direction.

[0165] Furthermore, since the piezoelectric layer 70 and the fourth electrode 80 are the same as in Embodiment 1 described above, repeated descriptions are omitted. That is, the fourth electrode 80 is a common electrode for a plurality of active parts, namely a plurality of first active parts 311, a plurality of second active parts 312, and a plurality of third active parts 313.

[0166] Regarding the drive signal for driving the recording head 2 having such a piezoelectric actuator 300, refer to... Figure 18 To explain further. Additionally... Figure 18 This represents the driving waveforms of the bias voltage, the fourth driving signal 204, and the fifth driving signal 205. Figures 19 to 21 A cross-sectional view along line C-C' to show the state of deformation of the piezoelectric actuator 300 and the vibrating plate 50 by the drive signal.

[0167] like Figure 18 As shown, the drive signal generation unit 216 generates a fourth drive signal 204 and a fifth drive signal 205 as drive signals. The fourth drive signal 204 corresponds to the "first drive signal" in Embodiment 2 and is supplied to the first electrode 61. The fifth drive signal 205 is supplied to the second electrode 62 and the third electrode 63.

[0168] These fourth drive signals 204 and fifth drive signals 205 are repeatedly generated from the drive signal generation unit 216 at unit periods T defined by the clock signal oscillating from the oscillation circuit 215. The unit period T is also called the ejection period T or the recording period T, and corresponds to one pixel of an image or the like printed on the medium S. In this embodiment, the unit period T is divided into two periods: a first period T1 and a second period T2.

[0169] Furthermore, the fourth drive signal 204 is a signal that generates a first jet pulse DP1 that drives the first active part 311 during a second period T2 within a recording cycle T, and is repeatedly generated every recording cycle T. The first jet pulse DP1 is selectively supplied to the first active part 311 corresponding to the pressure chamber 12 connected to the nozzle 21 that sprays the liquid. That is, the control unit generates an application pulse for each first active part 311 corresponding to each nozzle 21 based on the head control signal and the fourth drive signal 204, and supplies the application pulse to the piezoelectric actuator 300. In addition, the application pulse generated based on the fourth drive signal 204 is supplied to the first electrode 61 of the first active part 311. Furthermore, a bias potential vbs is supplied to the common electrode of the plurality of first active parts 311, namely the fourth electrode 80. Therefore, regarding the potential applied to the first electrode 61 by the application pulse, the bias potential vbs applied to the fourth electrode 80 becomes the reference potential. The bias potential vbs applied to the fourth electrode 80 corresponds to the "second potential" described in the technical solution.

[0170] The first jet pulse DP1 includes a third contraction element P20, a third contraction maintenance element P21, and a third recovery element P22. Furthermore, the application pulse generated according to the fourth drive signal 204 always supplies an intermediate potential, i.e., the tenth potential V, to the first electrode 61 when the jet pulse DP is not supplied. 10 Therefore, within a unit period T of the fourth drive signal 204, a tenth potential V is supplied before and after the first injection pulse DP1. 10 The sixth reference element B6 and the seventh reference element B7 are generated. That is, the fourth drive signal 204 sequentially generates the sixth reference element B6, the first injection pulse DP1, and the seventh reference element B7 within a unit period T. Furthermore, the sixth reference element B6 is generated within a period including the first period T1.

[0171] In the sixth reference element B6 and the seventh reference element B7, a tenth potential V, which is less than the bias potential Vbs, is continuously applied to the first electrode 61. 10 Thus, as Figure 19 As shown, the piezoelectric actuator 300 and the vibrating plate 50 are maintained in a state of flexural deformation toward the pressure chamber 12, i.e., in the +Z direction. Thus, the volume of the pressure chamber 12 is maintained at a tenth volume, which is smaller than the reference volume.

[0172] The third contraction element P20 of the first jet pulse DP1 is directed towards the first electrode 61 from the tenth potential V. 10 Up to the eleventh potential V 11 Apply a potential in such a way as Figure 21 As shown, the piezoelectric actuator 300 and the vibrating plate 50 are deformed in the +Z direction. As a result, the volume of the pressure chamber 12 shrinks from the tenth volume to the eleventh volume.

[0173] The third contraction maintenance element P21 continuously applies the eleventh potential V to the first electrode 61. 11 Meanwhile, the volume of the pressure chamber 12, which has expanded through the third contraction element P20, is maintained at a fixed eleventh volume for a fixed time.

[0174] The third recovery element P22 is applied to the first electrode 61 from the eleventh potential V. 11 Up to the tenth potential V 10 A potential is applied in a manner that causes the piezoelectric actuator 300 and the vibrating plate 50 to deform in the +Z direction. As a result, the volume of the pressure chamber 12 shrinks from the eleventh volume to the tenth volume and then recovers.

[0175] The fourth drive signal 204 is a signal that generates a second jet pulse DP2 that drives the second active part 312 and the third active part 313 during a first period T1 within a recording cycle T, and is repeatedly generated every recording cycle T. The second jet pulse DP2 is selectively supplied to the second active part 312 and the third active part 313 corresponding to the pressure chamber 12 connected to the nozzle 21 that sprays the liquid. That is, the control unit generates an application pulse for each group of second active parts 312 and third active parts 313 corresponding to each nozzle 21 based on the head control signal and the fifth drive signal 205, and supplies the application pulse to the piezoelectric actuator 300. In addition, the application pulse generated based on the fifth drive signal 205 is supplied to the second electrode 62 and the third electrode 63 of the second active part 312 and the third active part 313. In this embodiment, the application pulse is simultaneously supplied to a group of second electrodes 62 and third electrodes 63 via a separate communication portion 64A. Furthermore, a bias potential vbs is supplied to the common electrode 80 of the plurality of second active parts 312 and the plurality of third active parts 313. Therefore, the bias potential vbs applied to the fourth electrode 80 becomes the reference potential with respect to the potentials applied to the second electrodes 62 and the third electrodes 63 by applying pulses. In addition, the second jet pulse DP2 is generated during the first period T1 during which the first jet pulse DP1 is not generated in the fourth drive signal 204. That is, the first jet pulse DP1 and the second jet pulse DP2 are not input simultaneously.

[0176] The second injection pulse DP2 includes a fourth expansion element P30, a fourth expansion maintenance element P31, and a fourth recovery element P32. Furthermore, the application pulse generated according to the fourth drive signal 204 always supplies an intermediate potential, i.e., the twelfth potential V, to the second electrode 62 and the third electrode 63 when the second injection pulse DP2 is not supplied. 12 Therefore, within a unit period T of the fourth drive signal 204, a twelfth potential V is supplied before and after the second injection pulse DP2. 12 The eighth reference element B8 and the ninth reference element B9 are generated. That is, the fifth drive signal 205 generates the eighth reference element B8, the second injection pulse DP2, and the ninth reference element B9 sequentially within a unit period T. Furthermore, the ninth reference element B9 is generated during the second period T2 of the fourth drive signal 204, which includes the generation of the first injection pulse DP1.

[0177] The eighth reference element B8 and the ninth reference element B9 supply the second electrode 62 and the third electrode 63 with the twelfth potential V, which is the same as the bias potential Vbs. 12The state of not driving the second active part 312 and the third active part 313 is maintained. The ninth reference element B9 is supplied during the second period T2 when the piezoelectric actuator 300 is driven by the first jet pulse DP1. Therefore, during the period when the first active part 311 is driven by the first jet pulse DP1, the driving of the first active part 311 is not affected by not driving the second active part 312 and the third active part 313. In addition, since the second active part 312 and the third active part 313 are not driven by the eighth reference element B8 and the ninth reference element B9, the volume of the pressure chamber 12 in the eighth reference element B8 and the ninth reference element B9 is determined by the state of the fourth drive signal 204, that is, the driving state of the first active part 311.

[0178] The fourth expansion element P30 of the second jet pulse DP2 propels the second electrode 62 and the third electrode 63 from the twelfth potential V. 12 Up to the thirteenth potential V 13 Apply a potential in such a way as Figure 20 As shown, the piezoelectric actuator 300 and the vibrating plate 50 are deformed in the -Z direction. As a result, the volume of the pressure chamber 12 expands from its original volume to its twelfth volume. Furthermore, as described above, in the eighth reference element B8, such as... Figure 19 As shown, regarding the volume of pressure chamber 12, the tenth potential V is supplied to the first electrode 61 of the first active part 311 via the sixth reference element B6 of the fourth drive signal 204. 10 Thus, the volume of pressure chamber 12 becomes a tenth volume, reduced from the reference volume that has never been driven. Therefore, the fourth expansion element P30 expands from a tenth volume, reduced from the reference volume, to a twelfth volume, thereby being able to expand more than when expanding from the reference volume to the twelfth volume. Preferably, this thirteenth potential V... 13 Set as the eleventh potential V of the first jet pulse DP1 11 The same potential. Thirteenth potential V 13 The maximum potential of the second jet pulse DP2, the eleventh potential V 11 The maximum potential of the first injection pulse DP1 is set to the same potential. Therefore, it is preferable to set the maximum potentials of the first injection pulse DP1 and the second injection pulse DP2 to the same potential. By setting the maximum potentials of the first injection pulse DP1 and the second injection pulse DP2 to the same potential, the circuitry of the drive signal generation unit 216 can be simplified compared to the case where different potentials are generated.

[0179] The fourth expansion sustaining element P31 continuously applies the thirteenth potential V to the second electrode 62 and the third electrode 63. 13 The volume of the pressure chamber 12, which has been expanded by the fourth expansion element P30, is maintained at a fixed twelfth volume for a fixed time.

[0180] The fourth recovery element P32 is directed to the second electrode 62 and the third electrode 63 from the thirteenth potential V. 13 Up to the twelfth potential V 12 A potential is applied in a manner that causes the piezoelectric actuator 300 and the vibrating plate 50 to deform in the +Z direction. As a result, the volume of the pressure chamber 12 shrinks from the twelfth volume to the tenth volume.

[0181] The timing of the end of the second jet pulse DP2 is the same as the timing of the start of the first jet pulse DP1. That is, the timing of the end of the fourth recovery element P3 of the second jet pulse DP2 is the same as the timing of the start of the third contraction element P20 of the first jet pulse DP1. Alternatively, as long as the first jet pulse DP1 and the second jet pulse DP2 are not supplied simultaneously, the timing of the end of the fourth recovery element P32 of the second jet pulse DP2 and the timing of the start of the third contraction element P20 of the first jet pulse DP1 can be different. Preferably, for example, the interval between the end of the fourth recovery element P32 of the second jet pulse DP2 and the start of the third contraction element P20 of the first jet pulse DP1 is half the natural vibration period Tc of the pressure chamber 12. Therefore, when the meniscus in the nozzle 21 is oriented towards the +Z direction due to the residual vibration of the first jet pulse DP1, the second jet pulse DP2 can be supplied, suppressing the situation where the movement of the ink meniscus caused by the drive of the first jet pulse DP1 is hindered by the drive of the second jet pulse DP2, thereby enabling ink droplet ejection.

[0182] Furthermore, by supplying the first jet pulse DP1 and the second jet pulse DP2 to the first electrode 61, the second electrode 62 and the third electrode 63 respectively, ink droplets are ejected from the corresponding nozzles 21.

[0183] Specifically, firstly, from Figure 19 Starting from the state where the volume of pressure chamber 12 is the tenth volume, the fourth expansion element P30 of the second jet pulse DP2, as shown... Figure 20 As shown, the piezoelectric actuator 300 and the vibrating plate 50 are moved in the -Z direction, causing the volume of the pressure chamber 12 to expand from the tenth volume to the twelfth volume. As a result, the meniscus of the ink in the nozzle 21 is introduced to the pressure chamber 12 side, and ink is supplied to the pressure chamber 12 from the manifold 100 side.

[0184] Next, after the twelfth volume, which has been expanded by the fourth expansion holding element P31, is maintained for a fixed time, the piezoelectric actuator 300 and the vibrating plate 50 are moved in the +Z direction by the fourth recovery element P32, and the volume of the pressure chamber 12 is reduced from the twelfth volume to the tenth volume.

[0185] The third contraction element P20, supplied continuously with the first jet pulse DP1 in conjunction with the fourth recovery element P32, such as Figure 21 As shown, the piezoelectric actuator 300 and the vibrating plate 50 are moved further in the +Z direction, causing the volume of the pressure chamber 12 to shrink from the tenth volume to the eleventh volume. That is, by continuously supplying the fourth recovery element P32 of the second jet pulse DP2 and the third contraction element P20 of the first jet pulse DP1, the piezoelectric actuator 300 and the vibrating plate 50 cause the volume of the pressure chamber 12 to shrink rapidly from the twelfth volume to the eleventh volume. As a result, the ink within the pressure chamber 12 is pressurized, and ink droplets are ejected from the nozzle 21.

[0186] After the ink droplets are ejected, the eleventh volume is maintained for a fixed time by the third contraction maintenance element P21 of the first ejection pulse DP1. During the period when the third contraction maintenance element P21 is supplied, the ink pressure in the pressure chamber 12, which is reduced due to the ejection of ink droplets, repeatedly rises and falls while decaying due to its inherent vibration, and is restored to the original tenth volume by the third recovery element P22.

[0187] Thus, by driving the first active part 311 with the first jet pulse DP1 and driving the second active part 312 and the third active part 313 with the second jet pulse DP2 to eject ink droplets, the ejection volume when shrinking from the twelfth volume to the eleventh volume can be increased. Therefore, it is possible to eject ink droplets with larger ink weight.

[0188] Furthermore, ink droplets are ejected using a first ejection pulse DP1 that deforms the piezoelectric actuator 300 and the vibrating plate 50 in a convex +Z direction toward the pressure chamber 12, and a second ejection pulse DP2 that deforms the piezoelectric actuator 300 and the vibrating plate 50 in a convex -Z direction opposite to the pressure chamber 1. Therefore, compared to the case where ink droplets are ejected by deforming the piezoelectric actuator 300 in only one direction, it is difficult to generate residual strain in the piezoelectric layer 70 even with repeated driving of the piezoelectric actuator 300. Therefore, even with repeated driving of the piezoelectric actuator 300, the reduction in displacement can be suppressed.

[0189] Furthermore, since trapezoidal waves with relatively simple shapes can be used as the first jet pulse DP1 and the second jet pulse DP2, there is no need to generate waveforms with complex shapes as jet pulses, thereby simplifying the circuit structure of the drive signal generation unit 216 and making it easier to implement control.

[0190] As described above, the recording head 2, as an example of the piezoelectric device of the present invention, includes: a flow channel forming substrate 10, which is a substrate having recesses, i.e., pressure chambers 12, arranged in a first direction, i.e., the +X direction, communicating with nozzles 21 for jetting liquid; a vibrating plate 50; and a piezoelectric actuator 300. The piezoelectric actuator 300 sequentially includes: a first electrode 61; a second electrode 62 and a third electrode 63; and a fourth electrode 80. Furthermore, the piezoelectric actuator 300 has a piezoelectric layer 70 between the first electrode 61 and the fourth electrode 80, between the second electrode 62 and the fourth electrode 80, and between the third electrode 63 and the fourth electrode 80. In addition, it has a plurality of active portions, i.e., a first active portion 311, a second active portion 312, and a third active portion 313, which are sandwiched between the first electrode 61, the second electrode 62, the third electrode 63, and the fourth electrode 80, respectively. Furthermore, the second electrode 62 and the third electrode 63 are positioned at both ends of the pressure chamber 12 in the +X direction, extending from the edge of the region opposite the pressure chamber 12 to a position further outward than the pressure chamber 12 when viewed along the stacking direction, i.e., the -Z direction. Additionally, the first electrode 61 is formed between the second electrode 62 and the third electrode 63 in the +X direction, and the fourth electrode 80 constitutes a common electrode for multiple first active portions 311, second active portions 312, and third active portions 313.

[0191] Thus, by providing a first electrode 61 that drives the piezoelectric actuator 300 to deform toward the pressure chamber 12, and a second electrode 62 and a third electrode 63 that drive the piezoelectric actuator 300 to deform toward the opposite side of the pressure chamber 12, residual strain is less likely to occur in the piezoelectric layer 70, even with repeated driving of the piezoelectric actuator 300, compared to the case where the piezoelectric actuator 300 deforms only in any one direction along the Z-axis. Therefore, even with repeated driving of the piezoelectric actuator 300, the reduction in displacement can be suppressed. Therefore, even with repeated driving of the piezoelectric actuator 300, the reduction in ejection characteristics such as ink weight of the ink droplets ejected from the nozzle 21 can be suppressed, thereby enabling continued high-quality printing. Furthermore, compared to the case where the piezoelectric actuator 300 is driven in any one direction along the Z-axis, the displacement can be increased. Therefore, the weight of the ink droplets ejected from the nozzle 21 can be increased.

[0192] Furthermore, in the recording head 2 of this embodiment, it is preferable that the second electrode 62 and the third electrode 63 are individually provided electrodes for each of the second active portion 312 and the third active portion 313, which are active portions. That is, the second electrode 62 becomes an individual electrode for each of the plurality of second active portions 312, and the third electrode 63 becomes an individual electrode for each of the plurality of third active portions 313. In this way, by setting the second electrode 62 and the third electrode 63 as individual electrodes for the second active portion 312 and the third active portion 313, respectively, it is possible to selectively drive the second active portion 312 and the third active portion 313 for the plurality of pressure chambers 12.

[0193] Furthermore, in the recording head 2 of this embodiment, it is preferable that the second electrode 62 and the third electrode 63, which are provided for a single recess, i.e., the pressure chamber 12, are electrically connected on the flow channel forming substrate 10, which serves as the substrate. By electrically connecting the second electrode 62 and the third electrode 63, which are provided for a single pressure chamber 12, to the flow channel forming substrate 10, it is not necessary to independently provide the second individual lead electrode 94 for each of the second electrode 62 and the third electrode 63. Therefore, no space is needed on the flow channel forming substrate 10 for arranging the second individual lead electrode 94 or for connecting it to the wiring substrate 120. Thus, the number of second individual lead electrodes 94 can be reduced, thereby enabling miniaturization of the flow channel forming substrate 10.

[0194] Furthermore, as an example of the liquid jetting device of this embodiment, the inkjet recording device 1 includes: a flow channel forming substrate 10, which is a substrate having recesses, i.e., pressure chambers 12, formed in a first direction, i.e., the +X direction, communicating with nozzles 21 for jetting liquid; a vibrating plate 50; a piezoelectric actuator 300; and a control unit that drives the piezoelectric actuator 300. The piezoelectric actuator 300 sequentially includes: a first electrode 61; a second electrode 62 and a third electrode 63; and a fourth electrode 80. Furthermore, the piezoelectric actuator 300 has a piezoelectric layer 70 between the first electrode 61 and the fourth electrode 80, between the second electrode 62 and the fourth electrode 80, and between the third electrode 63 and the fourth electrode 80. In addition, it has a plurality of active portions, i.e., a first active portion 311, a second active portion 312, and a third active portion 313, which are sandwiched between the first electrode 61, the second electrode 62, the third electrode 63, and the fourth electrode 80, respectively. Furthermore, the second electrode 62 and the third electrode 63 are positioned at both ends of the pressure chamber 12 in the +X direction, extending from the edge of the region opposite the pressure chamber 12 to a position further outward than the pressure chamber 12 when viewed along the stacking direction, i.e., the -Z direction. Additionally, the first electrode 61 is formed between the second electrode 62 and the third electrode 63 in the +X direction, and the fourth electrode 80 constitutes a common electrode for multiple first active parts 311, second active parts 312, and third active parts 313. Furthermore, when the piezoelectric actuator 300 is deformed toward the pressure chamber 12, the control unit supplies a first injection pulse DP1 to the first electrode 61 and drives it. Furthermore, when the piezoelectric actuator 300 is deformed toward the opposite side of the pressure chamber 12, the control unit supplies a second injection pulse DP2 to the second electrode 62 and the third electrode 63 and drives them. Moreover, the control unit causes liquid to be ejected from the nozzle 21 via the first injection pulse DP1 and the second injection pulse DP2.

[0195] Thus, by using the first jet pulse DP1 and the second jet pulse DP2 to drive the piezoelectric actuator 300, the control unit makes it difficult to generate residual strain in the piezoelectric layer 70, even with repeated driving of the piezoelectric actuator 300, compared to the case where the piezoelectric actuator 300 is deformed only in any one direction along the Z-axis. Therefore, even with repeated driving of the piezoelectric actuator 300, the reduction in displacement can be suppressed. Therefore, even with repeated driving of the piezoelectric actuator 300, the reduction in jetting characteristics such as ink weight of the ink droplets ejected from the nozzle 21 can be suppressed, thereby enabling continued high-quality printing. Furthermore, compared to the case where the piezoelectric actuator 300 is driven only in any one direction along the Z-axis, the displacement can be increased. Therefore, the weight of the ink droplets ejected from the nozzle 21 can be increased.

[0196] Furthermore, in the inkjet recording device 1 of this embodiment, it is preferable that the control unit does not simultaneously supply the first jet pulse DP1 and the second jet pulse DP2. This allows for the suppression of unreasonable deformation of the piezoelectric actuator 300, thereby preventing damage such as cracks from forming in the actuator 300.

[0197] Furthermore, in the inkjet recording apparatus 1 of this embodiment, it is preferable that the maximum potentials of the first jet pulse DP1 and the second jet pulse DP2 are the same. That is, by using the maximum potential of the second jet pulse DP2, i.e., the thirteenth potential V... 13 The maximum potential of the first jet pulse DP1, i.e., the eleventh potential V 11 By setting the same potential, the circuit of the drive signal generation unit 216 can be simplified compared to the case where different potentials are generated.

[0198] Furthermore, although in the above example, the second electrode 62 and the third electrode 63, which are arranged corresponding to a pressure chamber 12, are electrically connected on the flow channel forming substrate 10, this is not a particular limitation. Here, a modified example of the recording head 2 of this embodiment will be presented... Figure 22 As shown in the image. Additionally... Figure 22 This is a top view of the convection channel forming substrate 10 viewed along the +Z direction, showing a modified example of the recording head 2 according to Embodiment 2.

[0199] like Figure 22 As shown, the second electrode 62 and the third electrode 63, which are disposed corresponding to a pressure chamber 12, are separately disposed on the flow channel forming substrate 10 in a manner that they are not electrically conductive. Furthermore, a second individual lead electrode 94 is disposed independently for each of the second electrode 62 and the third electrode 63.

[0200] Thus, by making the second electrode 62 and the third electrode 63 for a pressure chamber 12 electrically non-conductive on the flow channel forming substrate 10, different waveforms, i.e., different potentials, can be supplied to the second electrode 62 and the third electrode 63. For example, the thirteenth potential V of the second jet pulse DP2 supplied to the second electrode 62 and the third electrode 63 respectively can be controlled by making the second electrode 62 and the third electrode 63 electrically non-conductive. 13 This difference causes the flight direction of the ink droplets ejected from nozzle 21 to bend along the X-axis. Therefore, even if the ink droplets do not fly in the +Z direction perpendicular to the liquid ejection surface 20a, the thirteenth potential V of the second ejection pulse DP2 supplied to the second electrode 62 and the third electrode 63 can be adjusted by causing the ink droplets to fly in the +Z direction. 13 Adjustments can be made. That is, the thirteenth potential V supplied to the second electrode 62 and the third electrode 63 can be adjusted accordingly. 13Adjustments are made to regulate the flight direction of the ink droplets and suppress the offset of the ink droplets from their landing position on the medium S, thereby improving printing quality.

[0201] In other words, Figure 22 In the recording head 2 shown, preferably, the second electrode 62 and the third electrode 63 are not electrically connected on the flow channel forming substrate 10, which serves as the substrate. Accordingly, different potentials can be supplied to the second electrode 62 and the third electrode 63, and they can be driven. Therefore, by supplying different potentials to the second electrode 62 and the third electrode 63 and driving them, the angle of the ink droplet ejection direction, i.e., the tilt angle relative to the +Z direction towards the +X direction, can be adjusted.

[0202] Here, refer to Figure 23 A variation of the fifth drive signal 205 in this embodiment will be described. Furthermore, Figure 23 The driving waveforms represent a modified example of the bias potential VBS, the fourth driving signal 204, and the fifth driving signal 205.

[0203] like Figure 23 As shown, the fifth drive signal 205 has an eighth reference element B8, a second injection pulse DP2, and a ninth reference element B9.

[0204] The eighth reference element B8 and the ninth reference element B9 supply the second electrode 62 and the third electrode 63 with the potential supplied to the fourth electrode 80, which in this embodiment is the fourteenth potential V, which is the bias potential Vbs. 14 Here, the fourteenth potential V 14 This corresponds to the "first potential" in Implementation Method Two. Furthermore, the fourteenth potential V... 14 In this embodiment, the potential is less than the bias potential Vbs. That is, it satisfies the fourteenth potential V. 14 <The relationship between bias voltage VBS. Additionally, the fourteenth potential V...> 14 Preferably, it is set to the tenth potential V, which is related to the sixth reference element B6 and the seventh reference element B7 of the first jet pulse DP1. 10 The same potential. By passing the fourteenth potential V 14 and the tenth potential V 10 By setting the same potential, the circuit of the drive signal generation unit 216 can be simplified compared to the case where different potentials are generated.

[0205] Furthermore, the fourth expansion element P30 of the second jet pulse DP2 propels the second electrode 62 and the third electrode 63 from the fourteenth potential V. 14 Up to the thirteenth potential V 13 A potential is applied in a manner that allows for the application of a potential. Furthermore, the fourth recovery element P32 applies a potential from the thirteenth potential V to the second electrode 62 and the third electrode 63.13 up to the fourteenth potential V 14 The potential is applied in a manner that... The thirteenth potential V 13 Preferably, it is set to the tenth potential V of the first jet pulse DP1. 10 The first jet pulse DP1 and the second jet pulse DP2 have the same potential. Therefore, the first jet pulse DP1 and the second jet pulse DP2 can be set to have the same waveform shape. Here, "the first jet pulse DP1 and the second jet pulse DP2 have the same waveform shape" means that their respective lowest potential, highest potential, and slope are the same. Thus, by setting the first jet pulse DP1 and the second jet pulse DP2 to have the same waveform shape, it is easier to implement control of the drive signal generation unit 216.

[0206] Furthermore, by maintaining the supply of the fourteenth potential V to the second electrode 62 and the third electrode 63 by the eighth reference element B8 and the ninth reference element B9. 14 The state allows adjustment of the natural vibration period Tc of the pressure chamber 12. Here, the fourteenth potential V supplied to the second electrode 62 and the third electrode 63... 14 The magnitude of the voltage is inversely proportional to the magnitude of the natural oscillation period Tc of the pressure chamber 12. Therefore, by supplying the fourteenth potential V to the second electrode 62 and the third electrode 63... 14 This reduces the natural vibration period Tc of the pressure chamber 12, thereby enabling high-speed continuous ejection of ink droplets.

[0207] Furthermore, in a head unit that is modularized into multiple recording heads 2, even if there is a deviation in the inherent oscillation period Tc between the multiple recording heads 2, it is possible to detect the fourteenth potential V of each recording head 2. 14 Modifications are made to reduce the deviation of the inherent vibration period Tc between the multiple recording heads 2. Therefore, deviations in the ejection characteristics, such as ink weight and ejection speed, of the ink droplets ejected from the multiple recording heads 2 can be suppressed.

[0208] In addition, such as Figure 23 As shown, in the inkjet recording device 1, preferably, the control unit supplies a first drive signal, i.e., a fourth drive signal 204, which includes a first jet pulse DP1, to the first electrode 61. During the period when the control unit supplies the fourth drive signal 204 to the first electrode 61, it supplies a first potential, i.e., a fourteenth potential V, which is different from the potential supplied to the fourth electrode 80, to the second electrode 62 and the third electrode 63. 14 Accordingly, during the period when the fourth drive signal 204 is supplied to the first electrode 61, the fourteenth potential V is supplied to the second electrode 62 and the third electrode 63. 14By maintaining this state, the natural vibration period Tc of the pressure chamber 12 can be adjusted. Therefore, the natural vibration period Tc of the pressure chamber 12 can be reduced, enabling continuous high-speed ink droplet ejection. Furthermore, in an inkjet recording apparatus 1 comprising a head unit that modularizes multiple recording heads 2, or multiple recording heads 2, even if there is a deviation in the natural vibration period Tc between the multiple recording heads 2, the fourteenth potential V of each recording head 2 can be adjusted. 14 Modifications are made to reduce the deviation of the inherent oscillation period Tc between the multiple recording heads 2. Therefore, deviations in the ink ejection characteristics, such as ink weight and ejection speed, of the ink droplets ejected from the multiple recording heads 2 can be suppressed. Furthermore, although the example above specifies supplying a bias potential Vbs to the fourth electrode 80, this is not a limitation; the fourth electrode 80 may also be grounded (GND).

[0209] Furthermore, in the inkjet recording apparatus 1 of this embodiment, it is preferable that the control unit supplies the second potential, i.e., the bias potential Vbs, to the fourth electrode 80 during the period when the first drive signal, i.e., the fourth drive signal 204, is supplied, and the first potential, i.e., the fourteenth potential V... 14 Above the bias potential Vbs. Thus, by passing the fourteenth potential V... 14 By setting a potential greater than the bias potential Vbs, it is possible to suppress the application of an electric field opposite to the direction of the jet pulse DP to the piezoelectric actuator 300. Therefore, it is possible to suppress the occurrence of cracks or damage in the piezoelectric actuator 300.

[0210] like Figure 23 As shown, in the inkjet recording device 1, it is preferable that the first jet pulse DP1 and the second jet pulse DP2 have the same waveform shape. Accordingly, the control of the drive signal generation unit 216 can be simplified.

[0211] Furthermore, the fifth drive signal 205 may also include, in addition to the second injection pulse DP2, the vibration suppression pulse SVP described in Embodiment 1. A variation of such a fifth drive signal 205 is shown below. Figure 24 As shown in the image. Additionally... Figure 24 The waveforms represent the bias voltage VBS, the fourth drive signal 204, and the fifth drive signal 205.

[0212] like Figure 24 As shown, the unit period T of the fourth driving signal 204 and the fifth driving signal 205 is divided into three periods: the first period T1, the second period T2, and the third period T3.

[0213] The first injection pulse DP1 of the fourth drive signal 204 is generated during the second period T2. Furthermore, the second injection pulse DP2 of the fifth drive signal 205 is generated during the first period T1.

[0214] Furthermore, during the third period T3 of the fifth drive signal 205, a damping pulse SVP is generated. Additionally, the fifth drive signal 205 sequentially includes an eighth reference element B8, a second injection pulse DP2, a ninth reference element B9, a damping pulse SVP, and a tenth reference element B10. The tenth reference element B10 uses the same twelfth potential V as the eighth reference element B8 and the ninth reference element B9. 12 Supply is made to the second electrode 62 and the third electrode 63. Twelfth potential V 12 As described above, it is the same potential as the bias potential VBS.

[0215] The vibration suppression pulse SVP has a fifth expansion element P40, a fifth expansion maintenance element P41, and a fifth recovery element P42.

[0216] The fifth expansion element P40 is applied to the second electrode 62 and the third electrode 63 from the twelfth potential V. 12 Up to the fifteenth potential V 15 The potential is supplied in a manner that causes the piezoelectric actuator 300 and the vibrating plate 50 to deform in the opposite direction of the pressure chamber 12, i.e., the -Z direction. As a result, the volume of the pressure chamber 12 expands from the tenth volume to the thirteenth volume.

[0217] Furthermore, the fifteenth potential V of the fifth expansion element P40 15 Preferably, it is set to the thirteenth potential V of the second jet pulse DP2. 13 The same potential. By using the fifteenth potential V 15 and the thirteenth potential V 13 By setting the same potential, the circuit of the drive signal generation unit 216 can be simplified compared to the case where different potentials are generated.

[0218] The fifth expansion sustaining element P41 continuously applies the fifteenth potential V to the second electrode 62 and the third electrode 63. 15 Meanwhile, the volume of the pressure chamber 12, which has been expanded by the fifth expansion element P40, is maintained at a fixed volume for a fixed time.

[0219] The fifth recovery element P42 is directed to the second electrode 62 and the third electrode 63 from the fifteenth potential V. 15 Up to the twelfth potential V 12 A potential is applied in a manner that causes the piezoelectric actuator 300 and the vibrating plate 50 to deform in the +Z direction. As a result, the volume of the pressure chamber 12 shrinks from the thirteenth volume to the tenth volume and then recovers.

[0220] Thus, by adding a damping pulse SVP after the second ejection pulse DP2 and the first ejection pulse DP1, the residual vibration of the ink in the pressure chamber 12 after ink ejection from the nozzle 21 can be reduced in a short time. In other words, when the second active part 312 and the third active part 313 of the piezoelectric actuator 300 are driven by the damping pulse SVP, the residual vibration of the ink in the pressure chamber 12 after ink ejection from the nozzle 21 can be reduced in a short time. Figure 20 Similarly, the second active portion 312 and the third active portion 313 contract along the Z-axis, and the piezoelectric actuator 300 and the vibrating plate 50 deform in a convex manner protruding towards the opposite side of the pressure chamber 12, i.e., in the -Z direction. At this time, tensile stress is applied to the portion including the first active portion 311 sandwiched between the second active portion 312 and the third active portion 313, and the apparent Young's modulus increases. By increasing the apparent Young's modulus of the piezoelectric actuator 300, the residual vibration of the ink in the pressure chamber 12 after the ink droplets have been ejected can be made to converge within a short time.

[0221] Of course, the fifth drive signal 205 with the vibration damping pulse SVP is also related to... Figure 23 Similarly, the natural vibration period Tc of the pressure chamber 12 can be adjusted by setting the potential supplied to the second electrode 62 and the third electrode 63 to a different potential from the bias potential vbs in the eighth reference element B8, the ninth reference element B9 and the tenth reference element B10.

[0222] like Figure 24 As shown, in the inkjet recording device 1, preferably, after supplying the first jet pulse DP1 and the second jet pulse DP2, the control unit supplies a damping pulse SVP to the second electrode 62 and the third electrode 63 in a manner that prevents liquid from being ejected from the nozzle 21. Accordingly, by adding the damping pulse SVP after the jet pulse DP, the apparent Young's modulus of the piezoelectric layer 70 can be increased, and the residual vibrations after the first jet pulse DP1 and the second jet pulse DP2 can be converged in a short time. Therefore, ink droplets can be repeatedly ejected in a short time, thereby achieving high-speed continuous jetting.

[0223] Alternatively, a damping pulse (SVP) can be supplied to the second electrode 62 and the third electrode 63, which correspond to the pressure chamber 12 that does not eject ink droplets. This allows for micro-vibration of the ink near the pressure chamber 12 and the nozzle 21, suppressing the sedimentation of components contained in the ink and preventing the retention of thickened ink, thereby suppressing poor ink droplet ejection caused by thickened ink.

[0224] Furthermore, through this embodiment Figure 18 , Figure 23 as well as Figure 24The drive signal shown can also be used in the structure of Embodiment 1 described above, that is, in a structure where the second electrode 62 forms a common electrode for multiple second active parts 312 and the third electrode 63 forms a common electrode for multiple third active parts 313. In other words, the control unit only needs to supply the fourth drive signal 204 to the first electrode 61, which forms an individual electrode, and supply the fifth drive signal 205 to the second electrode 62 and the third electrode 63, which form a common electrode. Although the second ejection pulse DP2 is also supplied to the second active parts 312 and the third active parts 313, which do not eject ink droplets, as long as it is set so that ink droplets are not ejected only by the second ejection pulse DP2, in other words, as long as it is set so that ink droplets are ejected only when combined with the first ejection pulse DP1, ink droplets can be selectively ejected from the nozzle 21. Furthermore, by supplying only the second jet pulse DP2, which also functions as a micro-vibration pulse, the ink near the nozzle 21 can be micro-vibrated by driving the second active part 312 and the third active part 313, which correspond to the nozzle 21 that does not jet ink droplets, using the second jet pulse DP2. Therefore, sedimentation of components contained in the ink near the pressure chamber 12 and the nozzle 21 can be suppressed, and retention of thickened ink can be suppressed, thereby suppressing poor ink droplet jetting caused by thickened ink. Of course, it is also possible to supply the second jet pulse DP2, which is a micro-vibration pulse, to the second active part 312 and the third active part 313, which constitute the individual electrodes of this embodiment.

[0225] Other implementation methods

[0226] The various embodiments of the present invention have been described above, but the basic structure of the present invention is not limited to the above description.

[0227] Here, the piezoelectric actuator 300 and the vibrating plate 50 are not limited to the above-described contents. Here, a modified example of the piezoelectric actuator 300 and the vibrating plate 50 is presented. Figures 25 to 30 As shown in the image. Additionally... Figures 25 to 29 This is a cross-sectional view of the main portion of the recording head 2 according to other embodiments of the present invention. Furthermore, Figure 30 This is a top view of the flow channel forming substrate 10 according to another embodiment of the present invention, viewed along the +Z direction. Furthermore, the same reference numerals are used for components identical to those in the embodiments described above, and repeated descriptions are omitted.

[0228] like Figure 25As shown, on the side of the fourth electrode 80 opposite to the piezoelectric layer 70, i.e., on the -Z direction surface, a concave groove 81 is formed in the +X direction between the first electrode 61 and the second electrode 62, and between the first electrode 61 and the third electrode 63. For example, the piezoelectric layer 70 can be formed on the first electrode 61, the second electrode 62, and the third electrode 63 using a liquid phase film formation method such as sol-gel or MOD, and the concave groove 71 can be formed on the -Z direction surface of the piezoelectric layer 70, and the fourth electrode 80 can be formed on the -Z direction surface of the piezoelectric layer 70 where the concave groove 71 is formed, thereby forming the groove 81. Of course, the groove 81 can also be formed in the first and second embodiments described above. In addition, the piezoelectric layer 70 can be planarized by grinding the -Z direction surface using chemical mechanical polishing (CMP), without forming the groove 81 on the fourth electrode 80. Furthermore, if the surface of the piezoelectric layer 70 in the -Z direction is flat, the recess 71 and the groove 81 can be formed by locally etching the surface of the piezoelectric layer 70 in the -Z direction via a mask.

[0229] exist Figure 25 In the recording head 2 shown, it is preferable that a concave groove 81 is formed on the surface of the fourth electrode 80 on the side opposite to the piezoelectric layer 70 in the first direction, i.e., the +X direction, between the first electrode 61 and the second electrode 62 and between the first electrode 61 and the third electrode 63, because this arrangement makes it easy to deform.

[0230] Furthermore, the vibrating plate 50 is preferably characterized by a lower Young's modulus compared to the piezoelectric layer 70. For example, in the embodiments described above, the vibrating plate 50 comprises zirconium oxide (ZrO2). X The insulating film 52 and the piezoelectric layer 70 use lead zirconate titanate (PZT). Therefore, the Young's modulus of the vibrating plate 50 is lower than that of the piezoelectric layer 70. Thus, as... Figure 26 As shown, when observed along the +Z direction, in the region corresponding to the pressure chamber 12, the thickness of the vibrating plate 50 in the +Z direction is thinner at both ends in the +X direction compared to the central portion. That is, when observed along the -Z direction, the vibrating plate 50 has a first vibrating portion 50a with a thickness of d1 disposed in the region overlapping with the first electrode 61, and a second vibrating portion 50b with a thickness of d2 disposed in the regions overlapping with the second electrode 62 and the third electrode 63, satisfying the relationship d1 > d2.

[0231] The first vibrating portion 50a and the second vibrating portion 50b are formed such that the surface in the +Z direction is flat. Compared with the second vibrating portion 50b, the first vibrating portion 50a protrudes further towards the opposite side of the pressure chamber 12, i.e., in the -Z direction, resulting in a thicker film. Therefore, in the +Z direction, the distance t1 between the first electrode 61 and the fourth electrode 80 is narrower than the distance t2 between the second electrode 62 and the third electrode 63 and the fourth electrode 80. That is, the relationship t1 < t2 is satisfied. In addition, the distance t1 between the first electrode 61 and the fourth electrode 80, and the distance t2 between the second electrode 62 and the third electrode 63 and the fourth electrode 80 can be replaced by the thickness in the -Z direction of the piezoelectric layer 70.

[0232] also, Figure 26 The first vibrating part 50a and the second vibrating part 50b of the vibrating plate 50 can, for example, adjust the overall thickness d1 and d2 of the vibrating plate 50 by changing the thickness of the elastic membrane 51.

[0233] like Figure 26 As shown, a second electrode 62, a third electrode 63, a first electrode 61, and a fourth electrode 80 are arranged in the -Z direction, which is the stacking direction. Furthermore, it is preferable that, in the -Z direction, the distance t1 between the first electrode 61 and the fourth electrode 80 is narrower than the distance t2 between the second electrode 62 and the third electrode 63 and the fourth electrode 80. Thus, by making the distance t1 between the first electrode 61 and the fourth electrode 80 narrower than the distance t2, the electric field strength of the first active portion 311 can be increased. Furthermore, since an electric field in a direction inclined relative to the +Z direction can be applied to the piezoelectric layer 70 between the first electrode 61 and the fourth electrode 80 in the XZ plane defined by the X and Z axes, the driving efficiency can be improved.

[0234] In addition, it can also be like Figure 27 As shown, the first vibration portion 50a and the second vibration portion 50b are formed such that the surface in the -Z direction is flat. Compared with the second vibration portion 50b, the first vibration portion 50a protrudes further towards the pressure chamber 12, i.e., in the +Z direction, thereby increasing the film thickness. Furthermore, Figure 27 The first vibrating part 50a and the second vibrating part 50b of the vibrating plate 50 can, for example, adjust the overall thickness d1 and d2 of the vibrating plate 50 by changing the thickness of the elastic membrane 51.

[0235] In other words, such as Figure 26 as well as Figure 27As shown, preferably, the vibrating plate 50 has a larger Young's modulus than the piezoelectric layer 70. Regarding the vibrating plate 50, when viewed along the +Z direction, which is the stacking direction, in the region opposite the recess (pressure chamber 12), the thickness of the second vibrating portion 50b at both ends in the +X direction (first vibrating portion 50a) is thinner than that of the central portion (first vibrating portion 50a). Thus, by providing second vibrating portions 50b thinner than the first vibrating portion 50a at both ends in the +X direction of the vibrating plate 50, the vibrating plate 50 can be easily deformed along the Z-axis, allowing for a larger displacement with a lower voltage, thereby improving the so-called displacement efficiency.

[0236] Furthermore, by making the thickness d1 of the first vibrating part 50a of the vibrating plate 50 greater than the thickness d2 of the second vibrating part 50b, the first active part 311 can be moved away from the position of the neutral axis of the vibrating plate 50. Therefore, the displacement efficiency of the first active part 311 can be improved.

[0237] In addition, such as Figure 28 As shown, the thickness d2 of the second vibrating part 50b of the vibrating plate 50 can also be made thicker than the thickness d1 of the first vibrating part 50a, that is, the relationship d1 < d2 is satisfied. In such a structure, it can also achieve the same effect as Figure 27 The same effect.

[0238] In addition, such as Figure 26 As shown, regarding the piezoelectric layer 70, preferably, when viewed along the -Z direction, which is the stacking direction, in the region opposite the recess, i.e., the pressure chamber 12, the thickness in the -Z direction is thicker at both ends in the first direction (+X direction) than in the central portion. That is, preferably, the thickness t2 at both ends of the piezoelectric layer 70 is thicker than the thickness t1 in the central portion. Thus, by making the thickness t1 of the piezoelectric layer 70 between the first electrode 61 and the fourth electrode 80 thinner than the thickness t2 of the piezoelectric layer 70 between the second electrode 62 and the third electrode 63 and the fourth electrode 80, the electric field strength of the first active portion 311 can be increased. Furthermore, between the first electrode 61 and the fourth electrode 80, in the XZ plane defined by the X and Z axes, an electric field in a direction inclined relative to the +Z direction can be applied to the piezoelectric layer 70, thereby improving the driving efficiency.

[0239] In addition, such as Figure 28As shown, the thickness d1 of the first vibrating part 50a of the vibrating plate 50 can also be made thinner than the thickness d2 of the second vibrating part 50b. That is, the relationship d1 < d2 is satisfied. In this way, by making the thickness d1 of the first vibrating part 50a thinner than the thickness of the second vibrating part 50b, the driving efficiency of the first active part 311 can be improved. Furthermore, by making the thickness d2 of the most curved region of the vibrating plate 50, i.e., the second vibrating part 50b, thicker than the thickness d1 of the first vibrating part 50a, damage to the second vibrating part 50b when the piezoelectric actuator 300 is driven can be suppressed.

[0240] In addition, such as Figure 29 As shown, the piezoelectric actuator 300 has a first piezoelectric layer 70a, a second piezoelectric layer 70b, and a third piezoelectric layer 70c extending from the vibrating plate 50 towards the -Z direction. A first electrode 61 is disposed between the second piezoelectric layer 70b and the third piezoelectric layer 70c. Furthermore, a second electrode 62 and a third electrode 63 are disposed between the first piezoelectric layer 70a and the second piezoelectric layer 70b. That is, the second electrode 62, the third electrode 63, the first electrode 61, and the fourth electrode 80 are arranged towards the -Z direction. In other words, the first electrode 61, the second electrode 62, and the third electrode 63 are disposed at different positions in the -Z direction. Moreover, the distance t3 between the first electrode 61 and the fourth electrode 80 is narrower than the distance t4 between the second electrode 62 and the third electrode 63 and the fourth electrode 80. That is, the relationship t3 < t4 is satisfied. Furthermore, a first piezoelectric layer 70a and a second piezoelectric layer 70b are provided on the pressure chamber 12 side of the first electrode 61.

[0241] Furthermore, the first electrode 61, the second electrode 62, and the third electrode 63 are positioned in a non-overlapping manner when observed along the -Z direction. Additionally, in Figure 29 In the example shown, since the first electrode 61, the second electrode 62, and the third electrode 63 are configured at different positions in the -Z direction, the first electrode 61, the second electrode 62, and the third electrode 63 can also be configured at positions that partially overlap in the -Z direction.

[0242] exist Figure 29In the structure shown, the second electrode 62, the third electrode 63, the first electrode 61, and the fourth electrode 80 are arranged toward the -Z direction, which is the stacking direction. Furthermore, it is preferable that, in the -Z direction, the distance d3 between the first electrode 61 and the fourth electrode 80 is narrower than the distance d4 between the second electrode 62 and the third electrode 63 and the fourth electrode 80. Thus, by making the distance d3 between the first electrode 61 and the fourth electrode 80 narrower than the distance d4, the electric field strength of the first active portion 311 can be increased. Furthermore, since an electric field in a direction inclined relative to the +Z direction can be applied to the piezoelectric layer 70 between the first electrode 61 and the fourth electrode 80, within the XZ plane defined by the X and Z axes, the driving efficiency can be improved.

[0243] In addition, Figure 29 In the structure shown, it is preferable to have a first piezoelectric layer 70a and a second piezoelectric layer 70b as piezoelectric layers 70 in the recess of the first electrode 61, i.e., on the pressure chamber 12 side. Thus, by having the first piezoelectric layer 70a and the second piezoelectric layer 70b on the pressure chamber 12 side of the first electrode 61, the distance t3 between the first electrode 61 and the fourth electrode 80 can be narrower than the distance t4, thereby increasing the electric field strength of the first active portion 311. Furthermore, since an electric field inclined relative to the +Z direction can be applied to the piezoelectric layer 70 between the first electrode 61 and the fourth electrode 80 in the XZ plane defined by the X and Z axes, the driving efficiency can be improved. Additionally, since an electric field inclined relative to the +Z direction can be applied to and driven to the second piezoelectric layer 70b in the XZ plane between the first electrode 61 and the second electrode 62 and the third electrode 63, the driving efficiency can be improved.

[0244] In addition, such as Figure 30 As shown, when observed along the -Z direction, the first electrode 61 has a first central portion 61a at its center and first end portions 61b at both ends along the Y-axis at its position overlapping with the pressure chamber 12. The width w of the first central portion 61a in the +X direction is greater than the width w2 of the first end portions 61b. That is, the relationship w1 > w2 is satisfied. In other words, regarding the width of the first electrode 61 in the +X direction, when observed along the -Z direction, the central portion of the pressure chamber 12 in the +Y direction is wider than the two ends.

[0245] Furthermore, when observed along the -Z direction, the second electrode 62 has a second central portion 62a at its center and second end portions 62b at both ends along the Y-axis at a position overlapping with the pressure chamber 12. The width w3 of the second central portion 62a in the +X direction is greater than the width w4 of the second end portions 62b. That is, the relationship w3 > w4 is satisfied.

[0246] Furthermore, when observed along the -Z direction, the third electrode 63 has a third central portion 63a at its center and third end portions 63b at both ends along the Y-axis at its position overlapping with the pressure chamber 12. The width w5 of the third central portion 63a in the +X direction is greater than the width w6 of the third end portions 63b. That is, the relationship w5 > w6 is satisfied. In other words, regarding the width of the second electrode 62 and the third electrode 63 in the +X direction, when observed along the -Z direction, the central portion of the pressure chamber 12 in the +Y direction is wider than the two ends.

[0247] In addition, although Figure 30 In the example shown, for both the first electrode 61, the second electrode 62, and the third electrode 63, the width in the +X direction is set such that when viewed along the -Z direction, the central portion of the pressure chamber 12 in the +Y direction is wider than both ends. However, it is not specifically limited to this, as long as the width in the +X direction of any one of the first electrode 61, the second electrode 62, and the third electrode 63 satisfies the above-described structure.

[0248] like Figure 30 As shown, preferably, when viewed along the -Z direction (which is the stacking direction) of the first electrode 61 in the first direction (+X direction), the central portion of the pressure chamber 12 of the recess in the second direction (+Y direction), which is orthogonal to the +X direction, is wider than the two ends. Thus, by making the width w1 of the first central portion 61a of the first electrode 61 greater than the width w2 of the first end portions 61b at both ends, the area of ​​the XY plane of the first electrode 61 can be increased, thereby improving the driving efficiency. Furthermore, since the first end portions 61b have a narrower width w2 compared to the first central portion 61a, the electric field concentration at the ends of the first active portion 311 can be suppressed. Therefore, damage such as burn-off or cracking of the piezoelectric layer 70 can be suppressed.

[0249] In addition, such as Figure 30 As shown, preferably, when viewed along the -Z direction (which is the stacking direction) regarding the width of the second electrode 62 and the third electrode 63 in the first direction (+X direction), the central portion of the recess (pressure chamber 12) in the second direction (+Y direction), which is orthogonal to the +X direction, is wider than the two ends. Thus, by making the width w3 of the second central portion 62a and the width w5 of the third central portion 63a of the central portion of the second electrode 62 and the third electrode 63 wider than the width w4 of the second end portion 62b and the width w6 of the third end portion 63b at both ends, the area of ​​the XY plane of the second electrode 62 and the third electrode 63 can be increased, thereby improving the driving efficiency.

[0250] Furthermore, although the inkjet recording device 1 described above exemplifies a structure in which the recording head 2 is mounted on the transport body 7 and moves along the Y-axis, it is not particularly limited to this. For example, the present invention can also be applied to a so-called line recording device in which the recording head 2 is fixed and the medium S such as paper is moved in the sub-scanning direction, i.e., along the X-axis, to perform printing.

[0251] Furthermore, although the above embodiments are configured to supply a bias potential VBS to the fourth electrode 80, they are not particularly limited thereto, and the fourth electrode 80 may also be grounded (GND).

[0252] Furthermore, although the inkjet printing head was described as an example of a liquid ejector head and the inkjet recording device as an example of a liquid ejection device in the above embodiments, the present invention broadly applies to all liquid ejector heads and liquid ejection devices, and can of course be applied to liquid ejector heads and liquid ejection devices that eject liquids other than ink. Other examples of liquid ejector heads include: various printing heads used in image recording devices such as printers; color material ejector heads used in the manufacture of color filters for liquid crystal displays, etc.; electrode material ejector heads used in the electrode formation of organic EL displays, FEDs (field emission displays), etc.; and biological organic matter ejector heads used in the manufacture of biochips, etc., and can also be applied to liquid ejection devices equipped with such liquid ejector heads.

[0253] Symbol Explanation

[0254] 1…Inkjet recording device (liquid jet device); 2…Inkjet recording head (liquid jet head); 3…Liquid container; 4…Conveyor mechanism; 4a…Conveyor roller; 5…Control device; 6…Moving mechanism; 7…Conveyor body; 8…Conveyor belt; 10…Flow channel forming substrate; 11…Block; 12…Pressure chamber; 15…Connecting plate; 16…Nozzle connecting channel; 17…First manifold section; 18…Second manifold section; 19…Supply connecting channel; 20…Nozzle plate; 20a…Liquid jet surface; 21…Nozzle; 30…Protective substrate; 31…Holding part; 32…Through hole; 40…Housing component; 41…Recess; 42…Third manifold section; 43…Connection port; 44…Inlet port; 45…Moldable substrate; 46…Sealing film; 47 …Fixed substrate; 48…Opening; 49…Moldable portion; 50…Vibrating plate; 50a…First vibrating portion; 50b…Second vibrating portion; 51…Elastic membrane; 52…Insulating membrane; 61…First electrode; 61a…First central portion; 61b…First end; 62…Second electrode; 62a…Second central portion; 62b…Second end; 63…Third electrode; 63a…Third central portion; 63b…Third end; 64…Common connecting portion; 64A…Individual connecting portion; 70…Piezoelectric layer; 70a…First piezoelectric layer; 70b…Second piezoelectric layer; 70c…Third piezoelectric layer; 71…Recess; 80…Fourth electrode; 81…Groove; 91…First individual lead electrode; 92…First common lead electrode; 9 3…Second common lead electrode; 94…Second individual lead electrode; 100…Manifold; 120…Wiring board; 121…Drive circuit; 122…Shift register; 123…Latch circuit; 124…Level converter; 125…Switch; 201…First drive signal; 202…Second drive signal; 203…Third drive signal; 204…Fourth drive signal; 205…Fifth drive signal; 210…Printer controller; 211…External interface; 212A…Receiver buffer; 212B…Intermediate buffer; 212C…Output buffer; 214…Control processing unit; 215…Oscillator circuit; 216…Drive signal generation unit; 217…Internal interface; 220…Printing engine; 230…External device ; 300… Piezoelectric actuator; 311… First active part; 312… Second active part; 313… Third active part; B1… First reference element; B2… Second reference element; B3… Third reference element; B4… Fourth reference element; B5… Fifth reference element; B6… Sixth reference element; B7… Seventh reference element; B8… Eighth reference element; B9… Ninth reference element; B10… Tenth reference element; DP… Jet pulse; DP1… First jet pulse; DP2… Second jet pulse; P1… First expansion element; P2… First expansion maintenance element; P3… First contraction element; P4… First contraction maintenance element; P5… First recovery element; P10… Second expansion element; P11… Second expansion maintenance element;P12…Second recovery element; P20…Third contraction element; P21…Third contraction maintenance element; P22…Third recovery element; P30…Fourth expansion element; P31…Fourth expansion maintenance element; P32…Fourth recovery element; P40…Fifth expansion element; P41…Fifth expansion maintenance element; P42…Fifth recovery element; S…medium; SVP…vibration suppression pulse; T…unit period (ejection period, recording period); T1 to T3…First period to third period; Tc…natural vibration period; V1 to V; 15 …First potential to fifteenth potential; vbs…bias potential.

Claims

1. A piezoelectric device, characterized in that, The following are stacked in sequence: A substrate having multiple recesses arranged in a first direction; Vibrating plate; The first electrode, the second electrode, and the third electrode; piezoelectric layer; and Fourth electrode, The piezoelectric layer is disposed between the first electrode and the fourth electrode, between the second electrode and the fourth electrode, and between the third electrode and the fourth electrode. It has multiple active portions of the piezoelectric layer sandwiched between the first electrode, the second electrode, the third electrode, and the fourth electrode. The second electrode and the third electrode are positioned at both ends of the recess in the first direction, extending from the edge of the region opposite the recess to a location further outward than the recess when viewed along the stacking direction. The first electrode is formed in the first direction between the second electrode and the third electrode. The fourth electrode constitutes a common electrode for the plurality of active portions. The fourth electrode and each of the first, second, and third electrodes are arranged along the stacking direction and are located at a position farther from the vibrating plate than each of the first, second, and third electrodes.

2. The piezoelectric device as described in claim 1, characterized in that, The second electrode and the third electrode constitute separate electrodes that are independently provided for each of the active parts.

3. The piezoelectric device as described in claim 1 or 2, characterized in that, In the stacking direction, the spacing between the first electrode and the fourth electrode is the same as the spacing between the second electrode and the third electrode and the fourth electrode.

4. The piezoelectric device as described in claim 1 or 2, characterized in that, The second electrode, the third electrode, the first electrode, and the fourth electrode are arranged sequentially toward the stacking direction, wherein the spacing between the first electrode and the fourth electrode in the stacking direction is narrower than the spacing between the second electrode and the third electrode and the fourth electrode.

5. The piezoelectric device as described in claim 1, characterized in that, The piezoelectric layer is not present on the recessed side of the first electrode.

6. The piezoelectric device as described in claim 1, characterized in that, The piezoelectric layer is present on the recessed side of the first electrode.

7. The piezoelectric device as described in claim 1, characterized in that, When observed along the stacking direction, the first electrode, the second electrode, and the third electrode do not overlap with each other in the first direction.

8. The piezoelectric device as claimed in claim 1, characterized in that, When viewed along the stacking direction, the fourth electrode covers the recess in the first direction.

9. The piezoelectric device as claimed in claim 1, characterized in that, When viewed along the stacking direction, the recess has its long side oriented in a second direction orthogonal to the first direction.

10. The piezoelectric device as claimed in claim 1, characterized in that, Regarding the width of the first electrode in the first direction, when viewed along the stacking direction, the central portion of the recess in the second direction orthogonal to the first direction is wider than both ends.

11. The piezoelectric device as claimed in claim 1, characterized in that, Regarding the width of the second electrode and the third electrode in the first direction, when viewed along the stacking direction, the central portion of the recess in the second direction, which is orthogonal to the first direction, is wider than the two ends.

12. The piezoelectric device as claimed in claim 1, characterized in that, The Young's modulus of the vibrating plate is greater than that of the piezoelectric layer. When the vibrating plate is observed along the stacking direction, in the region opposite the recess, the thickness at both ends in the first direction is thinner than that in the central portion in the stacking direction.

13. The piezoelectric device as claimed in claim 12, characterized in that, When viewed along the stacking direction, in the region opposite the recess, the piezoelectric layer is thicker at both ends in the first direction than at the center.

14. The piezoelectric device as claimed in claim 1, characterized in that, The vibrating plate contains zirconium oxide.

15. The piezoelectric device as claimed in claim 1, characterized in that, The second electrode and the third electrode are not electrically conductive on the substrate.

16. The piezoelectric device as claimed in claim 1, characterized in that, The second electrode and the third electrode, which are disposed for one of the recesses, are electrically connected on the substrate.

17. A piezoelectric device, characterized in that, The following are stacked in sequence: A substrate having multiple recesses arranged in a first direction; Vibrating plate; The first electrode, the second electrode, and the third electrode; piezoelectric layer; and Fourth electrode, The piezoelectric layer is disposed between the first electrode and the fourth electrode, between the second electrode and the fourth electrode, and between the third electrode and the fourth electrode. It has multiple active portions of the piezoelectric layer sandwiched between the first electrode, the second electrode, the third electrode, and the fourth electrode. The second electrode and the third electrode are positioned at both ends of the recess in the first direction, extending from the edge of the region opposite the recess to a location further outward than the recess when viewed along the stacking direction. The first electrode is formed in the first direction between the second electrode and the third electrode. The fourth electrode constitutes a common electrode for the plurality of active portions. On the side of the fourth electrode opposite to the piezoelectric layer, a concave groove is formed in the first direction between the first electrode and the second electrode and between the first electrode and the third electrode.

18. A liquid injection device, characterized in that, It includes a substrate, a vibrating plate, a piezoelectric actuator, and a control unit. On the substrate, a plurality of pressure chambers communicating with nozzles for spraying liquid are arranged in a first direction. The piezoelectric actuator comprises, in sequence, a first electrode, a second electrode, and a third electrode; and a piezoelectric layer. and the fourth electrode, The piezoelectric layer is disposed between the first electrode and the fourth electrode, between the second electrode and the fourth electrode, and between the third electrode and the fourth electrode. The control unit drives the piezoelectric actuator. It has multiple active portions of the piezoelectric layer sandwiched between the first electrode, the second electrode, the third electrode, and the fourth electrode. The second electrode and the third electrode are disposed at both ends of the pressure chamber in the first direction, extending from the edge of the region opposite the pressure chamber to a location further outward than the pressure chamber when viewed along the stacking direction. The first electrode is formed in the first direction between the second electrode and the third electrode. The fourth electrode constitutes a common electrode for the plurality of active portions. The fourth electrode and each of the first, second, and third electrodes are arranged along the stacking direction and are located at a position farther from the vibrating plate than each of the first, second, and third electrodes. The first electrode is a separate electrode configured independently for each of the aforementioned active portions. The control unit performs the following actions, namely, When the piezoelectric actuator is deformed toward the pressure chamber side, a first jet pulse is supplied to the first electrode and driven. When the piezoelectric actuator is deformed toward the side opposite to the pressure chamber, a second jet pulse is supplied to the second electrode and the third electrode and driven. Liquid is ejected from the nozzle by the first jet pulse and the second jet pulse.

19. The liquid injection device as claimed in claim 18, characterized in that, The control unit does not simultaneously supply the first injection pulse and the second injection pulse.

20. The liquid injection device as claimed in claim 18 or 19, characterized in that, The maximum potentials of the first injection pulse and the second injection pulse are the same.

21. The liquid injection device as claimed in claim 18, characterized in that, The first injection pulse and the second injection pulse have the same waveform shape.

22. The liquid injection device as claimed in claim 18, characterized in that, The control unit supplies a first drive signal, which includes the first injection pulse, to the first electrode. During the period when the control unit supplies the first drive signal to the first electrode, it supplies a first potential, which is different from the potential supplied to the fourth electrode, to the second electrode and the third electrode.

23. The liquid injection device as claimed in claim 22, characterized in that, During the period when the first drive signal is supplied, the control unit supplies a second potential to the fourth electrode. The first potential is above the second potential.

24. The liquid injection device as claimed in claim 18, characterized in that, After supplying the first injection pulse and the second injection pulse, the control unit drives the piezoelectric actuator to supply damping pulses to the second electrode and the third electrode in a manner that prevents liquid from being ejected from the nozzle.

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